Merge branch 'main' into refactor/permissions-manager

# Conflicts:
#	management/server/account_test.go
#	management/server/http/handlers/networks/routers_handler.go

client/internal/acl/manager_test.go

@@ -19,6 +19,9 @@ import (
 var flowLogger = netflow.NewManager(nil, []byte{}, nil).GetLogger()
 
 func TestDefaultManager(t *testing.T) {
+	t.Setenv("NB_WG_KERNEL_DISABLED", "true")
+	t.Setenv(firewall.EnvForceUserspaceFirewall, "true")
+
 	networkMap := &mgmProto.NetworkMap{
 		FirewallRules: []*mgmProto.FirewallRule{
 			{
@@ -135,6 +138,7 @@ func TestDefaultManager(t *testing.T) {
 func TestDefaultManagerStateless(t *testing.T) {
 	// stateless currently only in userspace, so we have to disable kernel
 	t.Setenv("NB_WG_KERNEL_DISABLED", "true")
+	t.Setenv(firewall.EnvForceUserspaceFirewall, "true")
 	t.Setenv("NB_DISABLE_CONNTRACK", "true")
 
 	networkMap := &mgmProto.NetworkMap{
@@ -194,6 +198,7 @@ func TestDefaultManagerStateless(t *testing.T) {
 // This tests the full ACL manager -> uspfilter integration.
 func TestDenyRulesNotAccumulatedOnRepeatedApply(t *testing.T) {
 	t.Setenv("NB_WG_KERNEL_DISABLED", "true")
+	t.Setenv(firewall.EnvForceUserspaceFirewall, "true")
 
 	networkMap := &mgmProto.NetworkMap{
 		FirewallRules: []*mgmProto.FirewallRule{
@@ -258,6 +263,7 @@ func TestDenyRulesNotAccumulatedOnRepeatedApply(t *testing.T) {
 // up when they're removed from the network map in a subsequent update.
 func TestDenyRulesCleanedUpOnRemoval(t *testing.T) {
 	t.Setenv("NB_WG_KERNEL_DISABLED", "true")
+	t.Setenv(firewall.EnvForceUserspaceFirewall, "true")
 
 	ctrl := gomock.NewController(t)
 	defer ctrl.Finish()
@@ -339,6 +345,7 @@ func TestDenyRulesCleanedUpOnRemoval(t *testing.T) {
 // one added without leaking.
 func TestRuleUpdateChangingAction(t *testing.T) {
 	t.Setenv("NB_WG_KERNEL_DISABLED", "true")
+	t.Setenv(firewall.EnvForceUserspaceFirewall, "true")
 
 	ctrl := gomock.NewController(t)
 	defer ctrl.Finish()

client/internal/connect.go

@@ -111,6 +111,7 @@ func (c *ConnectClient) RunOniOS(
 	fileDescriptor int32,
 	networkChangeListener listener.NetworkChangeListener,
 	dnsManager dns.IosDnsManager,
+	dnsAddresses []netip.AddrPort,
 	stateFilePath string,
 ) error {
 	// Set GC percent to 5% to reduce memory usage as iOS only allows 50MB of memory for the extension.
@@ -120,6 +121,7 @@ func (c *ConnectClient) RunOniOS(
 		FileDescriptor:        fileDescriptor,
 		NetworkChangeListener: networkChangeListener,
 		DnsManager:            dnsManager,
+		HostDNSAddresses:      dnsAddresses,
 		StateFilePath:         stateFilePath,
 	}
 	return c.run(mobileDependency, nil, "")

client/internal/debug/debug.go

@@ -25,6 +25,7 @@ import (
 	"google.golang.org/protobuf/encoding/protojson"
 
 	"github.com/netbirdio/netbird/client/anonymize"
+	"github.com/netbirdio/netbird/client/configs"
 	"github.com/netbirdio/netbird/client/internal/peer"
 	"github.com/netbirdio/netbird/client/internal/profilemanager"
 	"github.com/netbirdio/netbird/client/internal/updater/installer"
@@ -52,6 +53,7 @@ resolved_domains.txt: Anonymized resolved domain IP addresses from the status re
 config.txt: Anonymized configuration information of the NetBird client.
 network_map.json: Anonymized sync response containing peer configurations, routes, DNS settings, and firewall rules.
 state.json: Anonymized client state dump containing netbird states for the active profile.
+service_params.json: Sanitized service install parameters (service.json). Sensitive environment variable values are masked. Only present when service.json exists.
 metrics.txt: Buffered client metrics in InfluxDB line protocol format. Only present when metrics collection is enabled. Peer identifiers are anonymized.
 mutex.prof: Mutex profiling information.
 goroutine.prof: Goroutine profiling information.
@@ -359,6 +361,10 @@ func (g *BundleGenerator) createArchive() error {
 		log.Errorf("failed to add corrupted state files to debug bundle: %v", err)
 	}
 
+	if err := g.addServiceParams(); err != nil {
+		log.Errorf("failed to add service params to debug bundle: %v", err)
+	}
+
 	if err := g.addMetrics(); err != nil {
 		log.Errorf("failed to add metrics to debug bundle: %v", err)
 	}
@@ -488,6 +494,90 @@ func (g *BundleGenerator) addConfig() error {
 	return nil
 }
 
+const (
+	serviceParamsFile    = "service.json"
+	serviceParamsBundle  = "service_params.json"
+	maskedValue          = "***"
+	envVarPrefix         = "NB_"
+	jsonKeyManagementURL = "management_url"
+	jsonKeyServiceEnv    = "service_env_vars"
+)
+
+var sensitiveEnvSubstrings = []string{"key", "token", "secret", "password", "credential"}
+
+// addServiceParams reads the service.json file and adds a sanitized version to the bundle.
+// Non-NB_ env vars and vars with sensitive names are masked. Other NB_ values are anonymized.
+func (g *BundleGenerator) addServiceParams() error {
+	path := filepath.Join(configs.StateDir, serviceParamsFile)
+
+	data, err := os.ReadFile(path)
+	if err != nil {
+		if os.IsNotExist(err) {
+			return nil
+		}
+		return fmt.Errorf("read service params: %w", err)
+	}
+
+	var params map[string]any
+	if err := json.Unmarshal(data, &params); err != nil {
+		return fmt.Errorf("parse service params: %w", err)
+	}
+
+	if g.anonymize {
+		if mgmtURL, ok := params[jsonKeyManagementURL].(string); ok && mgmtURL != "" {
+			params[jsonKeyManagementURL] = g.anonymizer.AnonymizeURI(mgmtURL)
+		}
+	}
+
+	g.sanitizeServiceEnvVars(params)
+
+	sanitizedData, err := json.MarshalIndent(params, "", "  ")
+	if err != nil {
+		return fmt.Errorf("marshal sanitized service params: %w", err)
+	}
+
+	if err := g.addFileToZip(bytes.NewReader(sanitizedData), serviceParamsBundle); err != nil {
+		return fmt.Errorf("add service params to zip: %w", err)
+	}
+
+	return nil
+}
+
+// sanitizeServiceEnvVars masks or anonymizes env var values in service params.
+// Non-NB_ vars and vars with sensitive names (key, token, etc.) are fully masked.
+// Other NB_ var values are passed through the anonymizer when anonymization is enabled.
+func (g *BundleGenerator) sanitizeServiceEnvVars(params map[string]any) {
+	envVars, ok := params[jsonKeyServiceEnv].(map[string]any)
+	if !ok {
+		return
+	}
+
+	sanitized := make(map[string]any, len(envVars))
+	for k, v := range envVars {
+		val, _ := v.(string)
+		switch {
+		case !strings.HasPrefix(k, envVarPrefix) || isSensitiveEnvVar(k):
+			sanitized[k] = maskedValue
+		case g.anonymize:
+			sanitized[k] = g.anonymizer.AnonymizeString(val)
+		default:
+			sanitized[k] = val
+		}
+	}
+	params[jsonKeyServiceEnv] = sanitized
+}
+
+// isSensitiveEnvVar returns true for env var names that may contain secrets.
+func isSensitiveEnvVar(key string) bool {
+	lower := strings.ToLower(key)
+	for _, s := range sensitiveEnvSubstrings {
+		if strings.Contains(lower, s) {
+			return true
+		}
+	}
+	return false
+}
+
 func (g *BundleGenerator) addCommonConfigFields(configContent *strings.Builder) {
 	configContent.WriteString("NetBird Client Configuration:\n\n")
 

client/internal/debug/debug_test.go

@@ -1,8 +1,12 @@
 package debug
 
 import (
+	"archive/zip"
+	"bytes"
 	"encoding/json"
 	"net"
+	"os"
+	"path/filepath"
 	"strings"
 	"testing"
 
@@ -10,6 +14,7 @@ import (
 	"github.com/stretchr/testify/require"
 
 	"github.com/netbirdio/netbird/client/anonymize"
+	"github.com/netbirdio/netbird/client/configs"
 	mgmProto "github.com/netbirdio/netbird/shared/management/proto"
 )
 
@@ -420,6 +425,226 @@ func TestAnonymizeNetworkMap(t *testing.T) {
 	}
 }
 
+func TestIsSensitiveEnvVar(t *testing.T) {
+	tests := []struct {
+		key       string
+		sensitive bool
+	}{
+		{"NB_SETUP_KEY", true},
+		{"NB_API_TOKEN", true},
+		{"NB_CLIENT_SECRET", true},
+		{"NB_PASSWORD", true},
+		{"NB_CREDENTIAL", true},
+		{"NB_LOG_LEVEL", false},
+		{"NB_MANAGEMENT_URL", false},
+		{"NB_HOSTNAME", false},
+		{"HOME", false},
+		{"PATH", false},
+	}
+	for _, tt := range tests {
+		t.Run(tt.key, func(t *testing.T) {
+			assert.Equal(t, tt.sensitive, isSensitiveEnvVar(tt.key))
+		})
+	}
+}
+
+func TestSanitizeServiceEnvVars(t *testing.T) {
+	tests := []struct {
+		name      string
+		anonymize bool
+		input     map[string]any
+		check     func(t *testing.T, params map[string]any)
+	}{
+		{
+			name:      "no env vars key",
+			anonymize: false,
+			input:     map[string]any{"management_url": "https://mgmt.example.com"},
+			check: func(t *testing.T, params map[string]any) {
+				t.Helper()
+				assert.Equal(t, "https://mgmt.example.com", params["management_url"], "non-env fields should be untouched")
+				_, ok := params[jsonKeyServiceEnv]
+				assert.False(t, ok, "service_env_vars should not be added")
+			},
+		},
+		{
+			name:      "non-NB vars are masked",
+			anonymize: false,
+			input: map[string]any{
+				jsonKeyServiceEnv: map[string]any{
+					"HOME":       "/root",
+					"PATH":       "/usr/bin",
+					"NB_LOG_LEVEL": "debug",
+				},
+			},
+			check: func(t *testing.T, params map[string]any) {
+				t.Helper()
+				env := params[jsonKeyServiceEnv].(map[string]any)
+				assert.Equal(t, maskedValue, env["HOME"], "non-NB_ var should be masked")
+				assert.Equal(t, maskedValue, env["PATH"], "non-NB_ var should be masked")
+				assert.Equal(t, "debug", env["NB_LOG_LEVEL"], "safe NB_ var should pass through")
+			},
+		},
+		{
+			name:      "sensitive NB vars are masked",
+			anonymize: false,
+			input: map[string]any{
+				jsonKeyServiceEnv: map[string]any{
+					"NB_SETUP_KEY":  "abc123",
+					"NB_API_TOKEN":  "tok_xyz",
+					"NB_LOG_LEVEL":  "info",
+				},
+			},
+			check: func(t *testing.T, params map[string]any) {
+				t.Helper()
+				env := params[jsonKeyServiceEnv].(map[string]any)
+				assert.Equal(t, maskedValue, env["NB_SETUP_KEY"], "sensitive NB_ var should be masked")
+				assert.Equal(t, maskedValue, env["NB_API_TOKEN"], "sensitive NB_ var should be masked")
+				assert.Equal(t, "info", env["NB_LOG_LEVEL"], "safe NB_ var should pass through")
+			},
+		},
+		{
+			name:      "safe NB vars anonymized when anonymize is true",
+			anonymize: true,
+			input: map[string]any{
+				jsonKeyServiceEnv: map[string]any{
+					"NB_MANAGEMENT_URL": "https://mgmt.example.com:443",
+					"NB_LOG_LEVEL":      "debug",
+					"NB_SETUP_KEY":      "secret",
+					"SOME_OTHER":        "val",
+				},
+			},
+			check: func(t *testing.T, params map[string]any) {
+				t.Helper()
+				env := params[jsonKeyServiceEnv].(map[string]any)
+				// Safe NB_ values should be anonymized (not the original, not masked)
+				mgmtVal := env["NB_MANAGEMENT_URL"].(string)
+				assert.NotEqual(t, "https://mgmt.example.com:443", mgmtVal, "should be anonymized")
+				assert.NotEqual(t, maskedValue, mgmtVal, "should not be masked")
+
+				logVal := env["NB_LOG_LEVEL"].(string)
+				assert.NotEqual(t, maskedValue, logVal, "safe NB_ var should not be masked")
+
+				// Sensitive and non-NB_ still masked
+				assert.Equal(t, maskedValue, env["NB_SETUP_KEY"])
+				assert.Equal(t, maskedValue, env["SOME_OTHER"])
+			},
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			anonymizer := anonymize.NewAnonymizer(anonymize.DefaultAddresses())
+			g := &BundleGenerator{
+				anonymize:  tt.anonymize,
+				anonymizer: anonymizer,
+			}
+			g.sanitizeServiceEnvVars(tt.input)
+			tt.check(t, tt.input)
+		})
+	}
+}
+
+func TestAddServiceParams(t *testing.T) {
+	t.Run("missing service.json returns nil", func(t *testing.T) {
+		g := &BundleGenerator{
+			anonymizer: anonymize.NewAnonymizer(anonymize.DefaultAddresses()),
+		}
+
+		origStateDir := configs.StateDir
+		configs.StateDir = t.TempDir()
+		t.Cleanup(func() { configs.StateDir = origStateDir })
+
+		err := g.addServiceParams()
+		assert.NoError(t, err)
+	})
+
+	t.Run("management_url anonymized when anonymize is true", func(t *testing.T) {
+		dir := t.TempDir()
+		origStateDir := configs.StateDir
+		configs.StateDir = dir
+		t.Cleanup(func() { configs.StateDir = origStateDir })
+
+		input := map[string]any{
+			jsonKeyManagementURL: "https://api.example.com:443",
+			jsonKeyServiceEnv: map[string]any{
+				"NB_LOG_LEVEL": "trace",
+			},
+		}
+		data, err := json.Marshal(input)
+		require.NoError(t, err)
+		require.NoError(t, os.WriteFile(filepath.Join(dir, serviceParamsFile), data, 0600))
+
+		var buf bytes.Buffer
+		zw := zip.NewWriter(&buf)
+
+		g := &BundleGenerator{
+			anonymize:  true,
+			anonymizer: anonymize.NewAnonymizer(anonymize.DefaultAddresses()),
+			archive:    zw,
+		}
+
+		require.NoError(t, g.addServiceParams())
+		require.NoError(t, zw.Close())
+
+		zr, err := zip.NewReader(bytes.NewReader(buf.Bytes()), int64(buf.Len()))
+		require.NoError(t, err)
+		require.Len(t, zr.File, 1)
+		assert.Equal(t, serviceParamsBundle, zr.File[0].Name)
+
+		rc, err := zr.File[0].Open()
+		require.NoError(t, err)
+		defer rc.Close()
+
+		var result map[string]any
+		require.NoError(t, json.NewDecoder(rc).Decode(&result))
+
+		mgmt := result[jsonKeyManagementURL].(string)
+		assert.NotEqual(t, "https://api.example.com:443", mgmt, "management_url should be anonymized")
+		assert.NotEmpty(t, mgmt)
+
+		env := result[jsonKeyServiceEnv].(map[string]any)
+		assert.NotEqual(t, maskedValue, env["NB_LOG_LEVEL"], "safe NB_ var should not be masked")
+	})
+
+	t.Run("management_url preserved when anonymize is false", func(t *testing.T) {
+		dir := t.TempDir()
+		origStateDir := configs.StateDir
+		configs.StateDir = dir
+		t.Cleanup(func() { configs.StateDir = origStateDir })
+
+		input := map[string]any{
+			jsonKeyManagementURL: "https://api.example.com:443",
+		}
+		data, err := json.Marshal(input)
+		require.NoError(t, err)
+		require.NoError(t, os.WriteFile(filepath.Join(dir, serviceParamsFile), data, 0600))
+
+		var buf bytes.Buffer
+		zw := zip.NewWriter(&buf)
+
+		g := &BundleGenerator{
+			anonymize:  false,
+			anonymizer: anonymize.NewAnonymizer(anonymize.DefaultAddresses()),
+			archive:    zw,
+		}
+
+		require.NoError(t, g.addServiceParams())
+		require.NoError(t, zw.Close())
+
+		zr, err := zip.NewReader(bytes.NewReader(buf.Bytes()), int64(buf.Len()))
+		require.NoError(t, err)
+
+		rc, err := zr.File[0].Open()
+		require.NoError(t, err)
+		defer rc.Close()
+
+		var result map[string]any
+		require.NoError(t, json.NewDecoder(rc).Decode(&result))
+
+		assert.Equal(t, "https://api.example.com:443", result[jsonKeyManagementURL], "management_url should be preserved")
+	})
+}
+
 // Helper function to check if IP is in CGNAT range
 func isInCGNATRange(ip net.IP) bool {
 	cgnat := net.IPNet{

client/internal/dns/handler_chain.go

@@ -73,6 +73,9 @@ func (w *ResponseWriterChain) WriteMsg(m *dns.Msg) error {
 		return nil
 	}
 	w.response = m
+	if m.MsgHdr.Truncated {
+		w.SetMeta("truncated", "true")
+	}
 	return w.ResponseWriter.WriteMsg(m)
 }
 
@@ -195,10 +198,14 @@ func (c *HandlerChain) ServeDNS(w dns.ResponseWriter, r *dns.Msg) {
 
 	startTime := time.Now()
 	requestID := resutil.GenerateRequestID()
-	logger := log.WithFields(log.Fields{
+	fields := log.Fields{
 		"request_id": requestID,
 		"dns_id":     fmt.Sprintf("%04x", r.Id),
-	})
+	}
+	if addr := w.RemoteAddr(); addr != nil {
+		fields["client"] = addr.String()
+	}
+	logger := log.WithFields(fields)
 
 	question := r.Question[0]
 	qname := strings.ToLower(question.Name)
@@ -261,9 +268,9 @@ func (c *HandlerChain) logResponse(logger *log.Entry, cw *ResponseWriterChain, q
 		meta += " " + k + "=" + v
 	}
 
-	logger.Tracef("response: domain=%s rcode=%s answers=%s%s took=%s",
+	logger.Tracef("response: domain=%s rcode=%s answers=%s size=%dB%s took=%s",
 		qname, dns.RcodeToString[cw.response.Rcode], resutil.FormatAnswers(cw.response.Answer),
-		meta, time.Since(startTime))
+		cw.response.Len(), meta, time.Since(startTime))
 }
 
 func (c *HandlerChain) isHandlerMatch(qname string, entry HandlerEntry) bool {

client/internal/dns/local/local_test.go

@@ -1263,9 +1263,9 @@ func TestLocalResolver_AuthoritativeFlag(t *testing.T) {
 	})
 }
 
-// TestLocalResolver_Stop tests cleanup on Stop
+// TestLocalResolver_Stop tests cleanup on GracefullyStop
 func TestLocalResolver_Stop(t *testing.T) {
-	t.Run("Stop clears all state", func(t *testing.T) {
+	t.Run("GracefullyStop clears all state", func(t *testing.T) {
 		resolver := NewResolver()
 		resolver.Update([]nbdns.CustomZone{{
 			Domain: "example.com.",
@@ -1285,7 +1285,7 @@ func TestLocalResolver_Stop(t *testing.T) {
 		assert.False(t, resolver.isInManagedZone("host.example.com."))
 	})
 
-	t.Run("Stop is safe to call multiple times", func(t *testing.T) {
+	t.Run("GracefullyStop is safe to call multiple times", func(t *testing.T) {
 		resolver := NewResolver()
 		resolver.Update([]nbdns.CustomZone{{
 			Domain: "example.com.",
@@ -1299,7 +1299,7 @@ func TestLocalResolver_Stop(t *testing.T) {
 		resolver.Stop()
 	})
 
-	t.Run("Stop cancels in-flight external resolution", func(t *testing.T) {
+	t.Run("GracefullyStop cancels in-flight external resolution", func(t *testing.T) {
 		resolver := NewResolver()
 
 		lookupStarted := make(chan struct{})

client/internal/dns/mock_server.go

@@ -90,6 +90,11 @@ func (m *MockServer) SetRouteChecker(func(netip.Addr) bool) {
 	// Mock implementation - no-op
 }
 
+// SetFirewall mock implementation of SetFirewall from Server interface
+func (m *MockServer) SetFirewall(Firewall) {
+	// Mock implementation - no-op
+}
+
 // BeginBatch mock implementation of BeginBatch from Server interface
 func (m *MockServer) BeginBatch() {
 	// Mock implementation - no-op

client/internal/dns/response_writer.go

@@ -104,3 +104,23 @@ func (r *responseWriter) TsigTimersOnly(bool) {
 // After a call to Hijack(), the DNS package will not do anything with the connection.
 func (r *responseWriter) Hijack() {
 }
+
+// remoteAddrFromPacket extracts the source IP:port from a decoded packet for logging.
+func remoteAddrFromPacket(packet gopacket.Packet) *net.UDPAddr {
+	var srcIP net.IP
+	if ipv4 := packet.Layer(layers.LayerTypeIPv4); ipv4 != nil {
+		srcIP = ipv4.(*layers.IPv4).SrcIP
+	} else if ipv6 := packet.Layer(layers.LayerTypeIPv6); ipv6 != nil {
+		srcIP = ipv6.(*layers.IPv6).SrcIP
+	}
+
+	var srcPort int
+	if udp := packet.Layer(layers.LayerTypeUDP); udp != nil {
+		srcPort = int(udp.(*layers.UDP).SrcPort)
+	}
+
+	if srcIP == nil {
+		return nil
+	}
+	return &net.UDPAddr{IP: srcIP, Port: srcPort}
+}

client/internal/dns/server.go

@@ -58,6 +58,7 @@ type Server interface {
 	UpdateServerConfig(domains dnsconfig.ServerDomains) error
 	PopulateManagementDomain(mgmtURL *url.URL) error
 	SetRouteChecker(func(netip.Addr) bool)
+	SetFirewall(Firewall)
 }
 
 type nsGroupsByDomain struct {
@@ -151,7 +152,7 @@ func NewDefaultServer(ctx context.Context, config DefaultServerConfig) (*Default
 	if config.WgInterface.IsUserspaceBind() {
 		dnsService = NewServiceViaMemory(config.WgInterface)
 	} else {
-		dnsService = newServiceViaListener(config.WgInterface, addrPort)
+		dnsService = newServiceViaListener(config.WgInterface, addrPort, nil)
 	}
 
 	server := newDefaultServer(ctx, config.WgInterface, dnsService, config.StatusRecorder, config.StateManager, config.DisableSys)
@@ -186,11 +187,16 @@ func NewDefaultServerIos(
 	ctx context.Context,
 	wgInterface WGIface,
 	iosDnsManager IosDnsManager,
+	hostsDnsList []netip.AddrPort,
 	statusRecorder *peer.Status,
 	disableSys bool,
 ) *DefaultServer {
+	log.Debugf("iOS host dns address list is: %v", hostsDnsList)
 	ds := newDefaultServer(ctx, wgInterface, NewServiceViaMemory(wgInterface), statusRecorder, nil, disableSys)
 	ds.iosDnsManager = iosDnsManager
+	ds.hostsDNSHolder.set(hostsDnsList)
+	ds.permanent = true
+	ds.addHostRootZone()
 	return ds
 }
 
@@ -374,6 +380,17 @@ func (s *DefaultServer) DnsIP() netip.Addr {
 	return s.service.RuntimeIP()
 }
 
+// SetFirewall sets the firewall used for DNS port DNAT rules.
+// This must be called before Initialize when using the listener-based service,
+// because the firewall is typically not available at construction time.
+func (s *DefaultServer) SetFirewall(fw Firewall) {
+	if svc, ok := s.service.(*serviceViaListener); ok {
+		svc.listenerFlagLock.Lock()
+		svc.firewall = fw
+		svc.listenerFlagLock.Unlock()
+	}
+}
+
 // Stop stops the server
 func (s *DefaultServer) Stop() {
 	s.probeMu.Lock()
@@ -395,8 +412,12 @@ func (s *DefaultServer) Stop() {
 	maps.Clear(s.extraDomains)
 }
 
-func (s *DefaultServer) disableDNS() error {
-	defer s.service.Stop()
+func (s *DefaultServer) disableDNS() (retErr error) {
+	defer func() {
+		if err := s.service.Stop(); err != nil {
+			retErr = errors.Join(retErr, fmt.Errorf("stop DNS service: %w", err))
+		}
+	}()
 
 	if s.isUsingNoopHostManager() {
 		return nil

client/internal/dns/server_test.go

@@ -476,8 +476,8 @@ func TestDNSFakeResolverHandleUpdates(t *testing.T) {
 
 	packetfilter := pfmock.NewMockPacketFilter(ctrl)
 	packetfilter.EXPECT().FilterOutbound(gomock.Any(), gomock.Any()).AnyTimes()
-	packetfilter.EXPECT().AddUDPPacketHook(gomock.Any(), gomock.Any(), gomock.Any(), gomock.Any())
-	packetfilter.EXPECT().RemovePacketHook(gomock.Any())
+	packetfilter.EXPECT().SetUDPPacketHook(gomock.Any(), gomock.Any(), gomock.Any()).AnyTimes()
+	packetfilter.EXPECT().SetTCPPacketHook(gomock.Any(), gomock.Any(), gomock.Any()).AnyTimes()
 
 	if err := wgIface.SetFilter(packetfilter); err != nil {
 		t.Errorf("set packet filter: %v", err)
@@ -1071,7 +1071,7 @@ func (m *mockHandler) ID() types.HandlerID                   { return types.Hand
 type mockService struct{}
 
 func (m *mockService) Listen() error                   { return nil }
-func (m *mockService) Stop()                           {}
+func (m *mockService) Stop() error                     { return nil }
 func (m *mockService) RuntimeIP() netip.Addr           { return netip.MustParseAddr("127.0.0.1") }
 func (m *mockService) RuntimePort() int                { return 53 }
 func (m *mockService) RegisterMux(string, dns.Handler) {}

client/internal/dns/service.go

@@ -4,15 +4,25 @@ import (
 	"net/netip"
 
 	"github.com/miekg/dns"
+
+	firewall "github.com/netbirdio/netbird/client/firewall/manager"
 )
 
 const (
 	DefaultPort = 53
 )
 
+// Firewall provides DNAT capabilities for DNS port redirection.
+// This is used when the DNS server cannot bind port 53 directly
+// and needs firewall rules to redirect traffic.
+type Firewall interface {
+	AddOutputDNAT(localAddr netip.Addr, protocol firewall.Protocol, sourcePort, targetPort uint16) error
+	RemoveOutputDNAT(localAddr netip.Addr, protocol firewall.Protocol, sourcePort, targetPort uint16) error
+}
+
 type service interface {
 	Listen() error
-	Stop()
+	Stop() error
 	RegisterMux(domain string, handler dns.Handler)
 	DeregisterMux(key string)
 	RuntimePort() int

client/internal/dns/service_listener.go

@@ -10,9 +10,13 @@ import (
 	"sync"
 	"time"
 
+	"github.com/hashicorp/go-multierror"
 	"github.com/miekg/dns"
 	log "github.com/sirupsen/logrus"
 
+	nberrors "github.com/netbirdio/netbird/client/errors"
+
+	firewall "github.com/netbirdio/netbird/client/firewall/manager"
 	"github.com/netbirdio/netbird/client/internal/ebpf"
 	ebpfMgr "github.com/netbirdio/netbird/client/internal/ebpf/manager"
 )
@@ -31,25 +35,33 @@ type serviceViaListener struct {
 	dnsMux            *dns.ServeMux
 	customAddr        *netip.AddrPort
 	server            *dns.Server
+	tcpServer         *dns.Server
 	listenIP          netip.Addr
 	listenPort        uint16
 	listenerIsRunning bool
 	listenerFlagLock  sync.Mutex
 	ebpfService       ebpfMgr.Manager
+	firewall          Firewall
+	tcpDNATConfigured bool
 }
 
-func newServiceViaListener(wgIface WGIface, customAddr *netip.AddrPort) *serviceViaListener {
+func newServiceViaListener(wgIface WGIface, customAddr *netip.AddrPort, fw Firewall) *serviceViaListener {
 	mux := dns.NewServeMux()
 
 	s := &serviceViaListener{
 		wgInterface: wgIface,
 		dnsMux:      mux,
 		customAddr:  customAddr,
+		firewall:    fw,
 		server: &dns.Server{
 			Net:     "udp",
 			Handler: mux,
 			UDPSize: 65535,
 		},
+		tcpServer: &dns.Server{
+			Net:     "tcp",
+			Handler: mux,
+		},
 	}
 
 	return s
@@ -70,43 +82,86 @@ func (s *serviceViaListener) Listen() error {
 		return fmt.Errorf("eval listen address: %w", err)
 	}
 	s.listenIP = s.listenIP.Unmap()
-	s.server.Addr = net.JoinHostPort(s.listenIP.String(), strconv.Itoa(int(s.listenPort)))
-	log.Debugf("starting dns on %s", s.server.Addr)
-	go func() {
-		s.setListenerStatus(true)
-		defer s.setListenerStatus(false)
+	addr := net.JoinHostPort(s.listenIP.String(), strconv.Itoa(int(s.listenPort)))
+	s.server.Addr = addr
+	s.tcpServer.Addr = addr
 
-		err := s.server.ListenAndServe()
-		if err != nil {
-			log.Errorf("dns server running with %d port returned an error: %v. Will not retry", s.listenPort, err)
+	log.Debugf("starting dns on %s (UDP + TCP)", addr)
+	s.listenerIsRunning = true
+
+	go func() {
+		if err := s.server.ListenAndServe(); err != nil {
+			log.Errorf("failed to run DNS UDP server on port %d: %v", s.listenPort, err)
+		}
+
+		s.listenerFlagLock.Lock()
+		unexpected := s.listenerIsRunning
+		s.listenerIsRunning = false
+		s.listenerFlagLock.Unlock()
+
+		if unexpected {
+			if err := s.tcpServer.Shutdown(); err != nil {
+				log.Debugf("failed to shutdown DNS TCP server: %v", err)
+			}
 		}
 	}()
 
+	go func() {
+		if err := s.tcpServer.ListenAndServe(); err != nil {
+			log.Errorf("failed to run DNS TCP server on port %d: %v", s.listenPort, err)
+		}
+	}()
+
+	// When eBPF redirects UDP port 53 to our listen port, TCP still needs
+	// a DNAT rule because eBPF only handles UDP.
+	if s.ebpfService != nil && s.firewall != nil && s.listenPort != DefaultPort {
+		if err := s.firewall.AddOutputDNAT(s.listenIP, firewall.ProtocolTCP, DefaultPort, s.listenPort); err != nil {
+			log.Warnf("failed to add DNS TCP DNAT rule, TCP DNS on port 53 will not work: %v", err)
+		} else {
+			s.tcpDNATConfigured = true
+			log.Infof("added DNS TCP DNAT rule: %s:%d -> %s:%d", s.listenIP, DefaultPort, s.listenIP, s.listenPort)
+		}
+	}
+
 	return nil
 }
 
-func (s *serviceViaListener) Stop() {
+func (s *serviceViaListener) Stop() error {
 	s.listenerFlagLock.Lock()
 	defer s.listenerFlagLock.Unlock()
 
 	if !s.listenerIsRunning {
-		return
+		return nil
 	}
+	s.listenerIsRunning = false
 
 	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
 	defer cancel()
 
-	err := s.server.ShutdownContext(ctx)
-	if err != nil {
-		log.Errorf("stopping dns server listener returned an error: %v", err)
+	var merr *multierror.Error
+
+	if err := s.server.ShutdownContext(ctx); err != nil {
+		merr = multierror.Append(merr, fmt.Errorf("stop DNS UDP server: %w", err))
+	}
+
+	if err := s.tcpServer.ShutdownContext(ctx); err != nil {
+		merr = multierror.Append(merr, fmt.Errorf("stop DNS TCP server: %w", err))
+	}
+
+	if s.tcpDNATConfigured && s.firewall != nil {
+		if err := s.firewall.RemoveOutputDNAT(s.listenIP, firewall.ProtocolTCP, DefaultPort, s.listenPort); err != nil {
+			merr = multierror.Append(merr, fmt.Errorf("remove DNS TCP DNAT rule: %w", err))
+		}
+		s.tcpDNATConfigured = false
 	}
 
 	if s.ebpfService != nil {
-		err = s.ebpfService.FreeDNSFwd()
-		if err != nil {
-			log.Errorf("stopping traffic forwarder returned an error: %v", err)
+		if err := s.ebpfService.FreeDNSFwd(); err != nil {
+			merr = multierror.Append(merr, fmt.Errorf("stop traffic forwarder: %w", err))
 		}
 	}
+
+	return nberrors.FormatErrorOrNil(merr)
 }
 
 func (s *serviceViaListener) RegisterMux(pattern string, handler dns.Handler) {
@@ -133,12 +188,6 @@ func (s *serviceViaListener) RuntimeIP() netip.Addr {
 	return s.listenIP
 }
 
-func (s *serviceViaListener) setListenerStatus(running bool) {
-	s.listenerFlagLock.Lock()
-	defer s.listenerFlagLock.Unlock()
-
-	s.listenerIsRunning = running
-}
 
 // evalListenAddress figure out the listen address for the DNS server
 // first check the 53 port availability on WG interface or lo, if not success
@@ -187,18 +236,28 @@ func (s *serviceViaListener) testFreePort(port int) (netip.Addr, bool) {
 }
 
 func (s *serviceViaListener) tryToBind(ip netip.Addr, port int) bool {
-	addrString := net.JoinHostPort(ip.String(), strconv.Itoa(port))
-	udpAddr := net.UDPAddrFromAddrPort(netip.MustParseAddrPort(addrString))
-	probeListener, err := net.ListenUDP("udp", udpAddr)
+	addrPort := netip.AddrPortFrom(ip, uint16(port))
+
+	udpAddr := net.UDPAddrFromAddrPort(addrPort)
+	udpLn, err := net.ListenUDP("udp", udpAddr)
 	if err != nil {
-		log.Warnf("binding dns on %s is not available, error: %s", addrString, err)
+		log.Warnf("binding dns UDP on %s is not available: %s", addrPort, err)
 		return false
 	}
-
-	err = probeListener.Close()
-	if err != nil {
-		log.Errorf("got an error closing the probe listener, error: %s", err)
+	if err := udpLn.Close(); err != nil {
+		log.Debugf("close UDP probe listener: %s", err)
 	}
+
+	tcpAddr := net.TCPAddrFromAddrPort(addrPort)
+	tcpLn, err := net.ListenTCP("tcp", tcpAddr)
+	if err != nil {
+		log.Warnf("binding dns TCP on %s is not available: %s", addrPort, err)
+		return false
+	}
+	if err := tcpLn.Close(); err != nil {
+		log.Debugf("close TCP probe listener: %s", err)
+	}
+
 	return true
 }
 

client/internal/dns/service_listener_test.go

@@ -0,0 +1,86 @@
+package dns
+
+import (
+	"fmt"
+	"net"
+	"net/netip"
+	"testing"
+	"time"
+
+	"github.com/miekg/dns"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestServiceViaListener_TCPAndUDP(t *testing.T) {
+	handler := dns.HandlerFunc(func(w dns.ResponseWriter, r *dns.Msg) {
+		m := new(dns.Msg)
+		m.SetReply(r)
+		m.Answer = append(m.Answer, &dns.A{
+			Hdr: dns.RR_Header{Name: r.Question[0].Name, Rrtype: dns.TypeA, Class: dns.ClassINET, Ttl: 60},
+			A:   net.ParseIP("192.0.2.1"),
+		})
+		if err := w.WriteMsg(m); err != nil {
+			t.Logf("write msg: %v", err)
+		}
+	})
+
+	// Create a service using a custom address to avoid needing root
+	svc := newServiceViaListener(nil, nil, nil)
+	svc.dnsMux.Handle(".", handler)
+
+	// Bind both transports up front to avoid TOCTOU races.
+	udpAddr := net.UDPAddrFromAddrPort(netip.AddrPortFrom(customIP, 0))
+	udpConn, err := net.ListenUDP("udp", udpAddr)
+	if err != nil {
+		t.Skip("cannot bind to 127.0.0.153, skipping")
+	}
+	port := uint16(udpConn.LocalAddr().(*net.UDPAddr).Port)
+
+	tcpAddr := net.TCPAddrFromAddrPort(netip.AddrPortFrom(customIP, port))
+	tcpLn, err := net.ListenTCP("tcp", tcpAddr)
+	if err != nil {
+		udpConn.Close()
+		t.Skip("cannot bind TCP on same port, skipping")
+	}
+
+	addr := fmt.Sprintf("%s:%d", customIP, port)
+	svc.server.PacketConn = udpConn
+	svc.tcpServer.Listener = tcpLn
+	svc.listenIP = customIP
+	svc.listenPort = port
+
+	go func() {
+		if err := svc.server.ActivateAndServe(); err != nil {
+			t.Logf("udp server: %v", err)
+		}
+	}()
+	go func() {
+		if err := svc.tcpServer.ActivateAndServe(); err != nil {
+			t.Logf("tcp server: %v", err)
+		}
+	}()
+	svc.listenerIsRunning = true
+
+	defer func() {
+		require.NoError(t, svc.Stop())
+	}()
+
+	q := new(dns.Msg).SetQuestion("example.com.", dns.TypeA)
+
+	// Test UDP query
+	udpClient := &dns.Client{Net: "udp", Timeout: 2 * time.Second}
+	udpResp, _, err := udpClient.Exchange(q, addr)
+	require.NoError(t, err, "UDP query should succeed")
+	require.NotNil(t, udpResp)
+	require.NotEmpty(t, udpResp.Answer)
+	assert.Contains(t, udpResp.Answer[0].String(), "192.0.2.1", "UDP response should contain expected IP")
+
+	// Test TCP query
+	tcpClient := &dns.Client{Net: "tcp", Timeout: 2 * time.Second}
+	tcpResp, _, err := tcpClient.Exchange(q, addr)
+	require.NoError(t, err, "TCP query should succeed")
+	require.NotNil(t, tcpResp)
+	require.NotEmpty(t, tcpResp.Answer)
+	assert.Contains(t, tcpResp.Answer[0].String(), "192.0.2.1", "TCP response should contain expected IP")
+}

client/internal/dns/service_memory.go

@@ -1,6 +1,7 @@
 package dns
 
 import (
+	"errors"
 	"fmt"
 	"net/netip"
 	"sync"
@@ -10,6 +11,7 @@ import (
 	"github.com/miekg/dns"
 	log "github.com/sirupsen/logrus"
 
+	"github.com/netbirdio/netbird/client/iface"
 	nbnet "github.com/netbirdio/netbird/client/net"
 )
 
@@ -18,7 +20,8 @@ type ServiceViaMemory struct {
 	dnsMux            *dns.ServeMux
 	runtimeIP         netip.Addr
 	runtimePort       int
-	udpFilterHookID   string
+	tcpDNS            *tcpDNSServer
+	tcpHookSet        bool
 	listenerIsRunning bool
 	listenerFlagLock  sync.Mutex
 }
@@ -28,14 +31,13 @@ func NewServiceViaMemory(wgIface WGIface) *ServiceViaMemory {
 	if err != nil {
 		log.Errorf("get last ip from network: %v", err)
 	}
-	s := &ServiceViaMemory{
+
+	return &ServiceViaMemory{
 		wgInterface: wgIface,
 		dnsMux:      dns.NewServeMux(),
-
 		runtimeIP:   lastIP,
 		runtimePort: DefaultPort,
 	}
-	return s
 }
 
 func (s *ServiceViaMemory) Listen() error {
@@ -46,10 +48,8 @@ func (s *ServiceViaMemory) Listen() error {
 		return nil
 	}
 
-	var err error
-	s.udpFilterHookID, err = s.filterDNSTraffic()
-	if err != nil {
-		return fmt.Errorf("filter dns traffice: %w", err)
+	if err := s.filterDNSTraffic(); err != nil {
+		return fmt.Errorf("filter dns traffic: %w", err)
 	}
 	s.listenerIsRunning = true
 
@@ -57,19 +57,29 @@ func (s *ServiceViaMemory) Listen() error {
 	return nil
 }
 
-func (s *ServiceViaMemory) Stop() {
+func (s *ServiceViaMemory) Stop() error {
 	s.listenerFlagLock.Lock()
 	defer s.listenerFlagLock.Unlock()
 
 	if !s.listenerIsRunning {
-		return
+		return nil
 	}
 
-	if err := s.wgInterface.GetFilter().RemovePacketHook(s.udpFilterHookID); err != nil {
-		log.Errorf("unable to remove DNS packet hook: %s", err)
+	filter := s.wgInterface.GetFilter()
+	if filter != nil {
+		filter.SetUDPPacketHook(s.runtimeIP, uint16(s.runtimePort), nil)
+		if s.tcpHookSet {
+			filter.SetTCPPacketHook(s.runtimeIP, uint16(s.runtimePort), nil)
+		}
+	}
+
+	if s.tcpDNS != nil {
+		s.tcpDNS.Stop()
 	}
 
 	s.listenerIsRunning = false
+
+	return nil
 }
 
 func (s *ServiceViaMemory) RegisterMux(pattern string, handler dns.Handler) {
@@ -88,10 +98,18 @@ func (s *ServiceViaMemory) RuntimeIP() netip.Addr {
 	return s.runtimeIP
 }
 
-func (s *ServiceViaMemory) filterDNSTraffic() (string, error) {
+func (s *ServiceViaMemory) filterDNSTraffic() error {
 	filter := s.wgInterface.GetFilter()
 	if filter == nil {
-		return "", fmt.Errorf("can't set DNS filter, filter not initialized")
+		return errors.New("DNS filter not initialized")
+	}
+
+	// Create TCP DNS server lazily here since the device may not exist at construction time.
+	if s.tcpDNS == nil {
+		if dev := s.wgInterface.GetDevice(); dev != nil {
+			// MTU only affects TCP segment sizing; DNS messages are small so this has no practical impact.
+			s.tcpDNS = newTCPDNSServer(s.dnsMux, dev.Device, s.runtimeIP, uint16(s.runtimePort), iface.DefaultMTU)
+		}
 	}
 
 	firstLayerDecoder := layers.LayerTypeIPv4
@@ -100,12 +118,16 @@ func (s *ServiceViaMemory) filterDNSTraffic() (string, error) {
 	}
 
 	hook := func(packetData []byte) bool {
-		// Decode the packet
 		packet := gopacket.NewPacket(packetData, firstLayerDecoder, gopacket.Default)
 
-		// Get the UDP layer
 		udpLayer := packet.Layer(layers.LayerTypeUDP)
-		udp := udpLayer.(*layers.UDP)
+		if udpLayer == nil {
+			return true
+		}
+		udp, ok := udpLayer.(*layers.UDP)
+		if !ok {
+			return true
+		}
 
 		msg := new(dns.Msg)
 		if err := msg.Unpack(udp.Payload); err != nil {
@@ -113,13 +135,30 @@ func (s *ServiceViaMemory) filterDNSTraffic() (string, error) {
 			return true
 		}
 
-		writer := responseWriter{
-			packet: packet,
-			device: s.wgInterface.GetDevice().Device,
+		dev := s.wgInterface.GetDevice()
+		if dev == nil {
+			return true
 		}
-		go s.dnsMux.ServeDNS(&writer, msg)
+
+		writer := &responseWriter{
+			remote: remoteAddrFromPacket(packet),
+			packet: packet,
+			device: dev.Device,
+		}
+		go s.dnsMux.ServeDNS(writer, msg)
 		return true
 	}
 
-	return filter.AddUDPPacketHook(false, s.runtimeIP, uint16(s.runtimePort), hook), nil
+	filter.SetUDPPacketHook(s.runtimeIP, uint16(s.runtimePort), hook)
+
+	if s.tcpDNS != nil {
+		tcpHook := func(packetData []byte) bool {
+			s.tcpDNS.InjectPacket(packetData)
+			return true
+		}
+		filter.SetTCPPacketHook(s.runtimeIP, uint16(s.runtimePort), tcpHook)
+		s.tcpHookSet = true
+	}
+
+	return nil
 }

client/internal/dns/tcpstack.go

@@ -0,0 +1,444 @@
+package dns
+
+import (
+	"errors"
+	"fmt"
+	"io"
+	"net"
+	"net/netip"
+	"sync"
+	"sync/atomic"
+	"time"
+
+	"github.com/miekg/dns"
+	log "github.com/sirupsen/logrus"
+	"golang.zx2c4.com/wireguard/tun"
+	"gvisor.dev/gvisor/pkg/buffer"
+	"gvisor.dev/gvisor/pkg/tcpip"
+	"gvisor.dev/gvisor/pkg/tcpip/adapters/gonet"
+	"gvisor.dev/gvisor/pkg/tcpip/header"
+	"gvisor.dev/gvisor/pkg/tcpip/network/ipv4"
+	"gvisor.dev/gvisor/pkg/tcpip/stack"
+	"gvisor.dev/gvisor/pkg/tcpip/transport/tcp"
+	"gvisor.dev/gvisor/pkg/waiter"
+)
+
+const (
+	dnsTCPReceiveWindow = 8192
+	dnsTCPMaxInFlight   = 16
+	dnsTCPIdleTimeout   = 30 * time.Second
+	dnsTCPReadTimeout   = 5 * time.Second
+)
+
+// tcpDNSServer is an on-demand TCP DNS server backed by a minimal gvisor stack.
+// It is started lazily when a truncated DNS response is detected and shuts down
+// after a period of inactivity to conserve resources.
+type tcpDNSServer struct {
+	mu     sync.Mutex
+	s      *stack.Stack
+	ep     *dnsEndpoint
+	mux    *dns.ServeMux
+	tunDev tun.Device
+	ip     netip.Addr
+	port   uint16
+	mtu    uint16
+
+	running bool
+	closed  bool
+	timerID uint64
+	timer   *time.Timer
+}
+
+func newTCPDNSServer(mux *dns.ServeMux, tunDev tun.Device, ip netip.Addr, port uint16, mtu uint16) *tcpDNSServer {
+	return &tcpDNSServer{
+		mux:    mux,
+		tunDev: tunDev,
+		ip:     ip,
+		port:   port,
+		mtu:    mtu,
+	}
+}
+
+// InjectPacket ensures the stack is running and delivers a raw IP packet into
+// the gvisor stack for TCP processing. Combining both operations under a single
+// lock prevents a race where the idle timer could stop the stack between
+// start and delivery.
+func (t *tcpDNSServer) InjectPacket(payload []byte) {
+	t.mu.Lock()
+	defer t.mu.Unlock()
+
+	if t.closed {
+		return
+	}
+
+	if !t.running {
+		if err := t.startLocked(); err != nil {
+			log.Errorf("failed to start TCP DNS stack: %v", err)
+			return
+		}
+		t.running = true
+		log.Debugf("TCP DNS stack started on %s:%d (triggered by %s)", t.ip, t.port, srcAddrFromPacket(payload))
+	}
+	t.resetTimerLocked()
+
+	ep := t.ep
+	if ep == nil || ep.dispatcher == nil {
+		return
+	}
+
+	pkt := stack.NewPacketBuffer(stack.PacketBufferOptions{
+		Payload: buffer.MakeWithData(payload),
+	})
+	// DeliverNetworkPacket takes ownership of the packet buffer; do not DecRef.
+	ep.dispatcher.DeliverNetworkPacket(ipv4.ProtocolNumber, pkt)
+}
+
+// Stop tears down the gvisor stack and releases resources permanently.
+// After Stop, InjectPacket becomes a no-op.
+func (t *tcpDNSServer) Stop() {
+	t.mu.Lock()
+	defer t.mu.Unlock()
+
+	t.stopLocked()
+	t.closed = true
+}
+
+func (t *tcpDNSServer) startLocked() error {
+	// TODO: add ipv6.NewProtocol when IPv6 overlay support lands.
+	s := stack.New(stack.Options{
+		NetworkProtocols:   []stack.NetworkProtocolFactory{ipv4.NewProtocol},
+		TransportProtocols: []stack.TransportProtocolFactory{tcp.NewProtocol},
+		HandleLocal:        false,
+	})
+
+	nicID := tcpip.NICID(1)
+	ep := &dnsEndpoint{
+		tunDev: t.tunDev,
+	}
+	ep.mtu.Store(uint32(t.mtu))
+
+	if err := s.CreateNIC(nicID, ep); err != nil {
+		s.Close()
+		s.Wait()
+		return fmt.Errorf("create NIC: %v", err)
+	}
+
+	protoAddr := tcpip.ProtocolAddress{
+		Protocol: ipv4.ProtocolNumber,
+		AddressWithPrefix: tcpip.AddressWithPrefix{
+			Address:   tcpip.AddrFromSlice(t.ip.AsSlice()),
+			PrefixLen: 32,
+		},
+	}
+	if err := s.AddProtocolAddress(nicID, protoAddr, stack.AddressProperties{}); err != nil {
+		s.Close()
+		s.Wait()
+		return fmt.Errorf("add protocol address: %s", err)
+	}
+
+	if err := s.SetPromiscuousMode(nicID, true); err != nil {
+		s.Close()
+		s.Wait()
+		return fmt.Errorf("set promiscuous mode: %s", err)
+	}
+	if err := s.SetSpoofing(nicID, true); err != nil {
+		s.Close()
+		s.Wait()
+		return fmt.Errorf("set spoofing: %s", err)
+	}
+
+	defaultSubnet, err := tcpip.NewSubnet(
+		tcpip.AddrFrom4([4]byte{0, 0, 0, 0}),
+		tcpip.MaskFromBytes([]byte{0, 0, 0, 0}),
+	)
+	if err != nil {
+		s.Close()
+		s.Wait()
+		return fmt.Errorf("create default subnet: %w", err)
+	}
+
+	s.SetRouteTable([]tcpip.Route{
+		{Destination: defaultSubnet, NIC: nicID},
+	})
+
+	tcpFwd := tcp.NewForwarder(s, dnsTCPReceiveWindow, dnsTCPMaxInFlight, func(r *tcp.ForwarderRequest) {
+		t.handleTCPDNS(r)
+	})
+	s.SetTransportProtocolHandler(tcp.ProtocolNumber, tcpFwd.HandlePacket)
+
+	t.s = s
+	t.ep = ep
+	return nil
+}
+
+func (t *tcpDNSServer) stopLocked() {
+	if !t.running {
+		return
+	}
+
+	if t.timer != nil {
+		t.timer.Stop()
+		t.timer = nil
+	}
+
+	if t.s != nil {
+		t.s.Close()
+		t.s.Wait()
+		t.s = nil
+	}
+	t.ep = nil
+	t.running = false
+
+	log.Debugf("TCP DNS stack stopped")
+}
+
+func (t *tcpDNSServer) resetTimerLocked() {
+	if t.timer != nil {
+		t.timer.Stop()
+	}
+	t.timerID++
+	id := t.timerID
+	t.timer = time.AfterFunc(dnsTCPIdleTimeout, func() {
+		t.mu.Lock()
+		defer t.mu.Unlock()
+
+		// Only stop if this timer is still the active one.
+		// A racing InjectPacket may have replaced it.
+		if t.timerID != id {
+			return
+		}
+		t.stopLocked()
+	})
+}
+
+func (t *tcpDNSServer) handleTCPDNS(r *tcp.ForwarderRequest) {
+	id := r.ID()
+
+	wq := waiter.Queue{}
+	ep, epErr := r.CreateEndpoint(&wq)
+	if epErr != nil {
+		log.Debugf("TCP DNS: failed to create endpoint: %v", epErr)
+		r.Complete(true)
+		return
+	}
+	r.Complete(false)
+
+	conn := gonet.NewTCPConn(&wq, ep)
+	defer func() {
+		if err := conn.Close(); err != nil {
+			log.Tracef("TCP DNS: close conn: %v", err)
+		}
+	}()
+
+	// Reset idle timer on activity
+	t.mu.Lock()
+	t.resetTimerLocked()
+	t.mu.Unlock()
+
+	localAddr := &net.TCPAddr{
+		IP:   id.LocalAddress.AsSlice(),
+		Port: int(id.LocalPort),
+	}
+	remoteAddr := &net.TCPAddr{
+		IP:   id.RemoteAddress.AsSlice(),
+		Port: int(id.RemotePort),
+	}
+
+	for {
+		if err := conn.SetReadDeadline(time.Now().Add(dnsTCPReadTimeout)); err != nil {
+			log.Debugf("TCP DNS: set deadline for %s: %v", remoteAddr, err)
+			break
+		}
+
+		msg, err := readTCPDNSMessage(conn)
+		if err != nil {
+			if !errors.Is(err, io.EOF) && !errors.Is(err, io.ErrUnexpectedEOF) {
+				log.Debugf("TCP DNS: read from %s: %v", remoteAddr, err)
+			}
+			break
+		}
+
+		writer := &tcpResponseWriter{
+			conn:       conn,
+			localAddr:  localAddr,
+			remoteAddr: remoteAddr,
+		}
+		t.mux.ServeDNS(writer, msg)
+	}
+}
+
+// dnsEndpoint implements stack.LinkEndpoint for writing packets back via the tun device.
+type dnsEndpoint struct {
+	dispatcher stack.NetworkDispatcher
+	tunDev     tun.Device
+	mtu        atomic.Uint32
+}
+
+func (e *dnsEndpoint) Attach(dispatcher stack.NetworkDispatcher)    { e.dispatcher = dispatcher }
+func (e *dnsEndpoint) IsAttached() bool                             { return e.dispatcher != nil }
+func (e *dnsEndpoint) MTU() uint32                                  { return e.mtu.Load() }
+func (e *dnsEndpoint) Capabilities() stack.LinkEndpointCapabilities { return stack.CapabilityNone }
+func (e *dnsEndpoint) MaxHeaderLength() uint16                      { return 0 }
+func (e *dnsEndpoint) LinkAddress() tcpip.LinkAddress               { return "" }
+func (e *dnsEndpoint) Wait()                                        { /* no async work */ }
+func (e *dnsEndpoint) ARPHardwareType() header.ARPHardwareType      { return header.ARPHardwareNone }
+func (e *dnsEndpoint) AddHeader(*stack.PacketBuffer)                { /* IP-level endpoint, no link header */ }
+func (e *dnsEndpoint) ParseHeader(*stack.PacketBuffer) bool         { return true }
+func (e *dnsEndpoint) Close()                                       { /* lifecycle managed by tcpDNSServer */ }
+func (e *dnsEndpoint) SetLinkAddress(tcpip.LinkAddress)             { /* no link address for tun */ }
+func (e *dnsEndpoint) SetMTU(mtu uint32)                            { e.mtu.Store(mtu) }
+func (e *dnsEndpoint) SetOnCloseAction(func())                      { /* not needed */ }
+
+const tunPacketOffset = 40
+
+func (e *dnsEndpoint) WritePackets(pkts stack.PacketBufferList) (int, tcpip.Error) {
+	var written int
+	for _, pkt := range pkts.AsSlice() {
+		data := stack.PayloadSince(pkt.NetworkHeader())
+		if data == nil {
+			continue
+		}
+
+		raw := data.AsSlice()
+		buf := make([]byte, tunPacketOffset, tunPacketOffset+len(raw))
+		buf = append(buf, raw...)
+		data.Release()
+
+		if _, err := e.tunDev.Write([][]byte{buf}, tunPacketOffset); err != nil {
+			log.Tracef("TCP DNS endpoint: failed to write packet: %v", err)
+			continue
+		}
+		written++
+	}
+	return written, nil
+}
+
+// tcpResponseWriter implements dns.ResponseWriter for TCP DNS connections.
+type tcpResponseWriter struct {
+	conn       *gonet.TCPConn
+	localAddr  net.Addr
+	remoteAddr net.Addr
+}
+
+func (w *tcpResponseWriter) LocalAddr() net.Addr {
+	return w.localAddr
+}
+
+func (w *tcpResponseWriter) RemoteAddr() net.Addr {
+	return w.remoteAddr
+}
+
+func (w *tcpResponseWriter) WriteMsg(msg *dns.Msg) error {
+	data, err := msg.Pack()
+	if err != nil {
+		return fmt.Errorf("pack: %w", err)
+	}
+
+	// DNS TCP: 2-byte length prefix + message
+	buf := make([]byte, 2+len(data))
+	buf[0] = byte(len(data) >> 8)
+	buf[1] = byte(len(data))
+	copy(buf[2:], data)
+
+	if _, err = w.conn.Write(buf); err != nil {
+		return err
+	}
+	return nil
+}
+
+func (w *tcpResponseWriter) Write(data []byte) (int, error) {
+	buf := make([]byte, 2+len(data))
+	buf[0] = byte(len(data) >> 8)
+	buf[1] = byte(len(data))
+	copy(buf[2:], data)
+	if _, err := w.conn.Write(buf); err != nil {
+		return 0, err
+	}
+	return len(data), nil
+}
+
+func (w *tcpResponseWriter) Close() error {
+	return w.conn.Close()
+}
+
+func (w *tcpResponseWriter) TsigStatus() error   { return nil }
+func (w *tcpResponseWriter) TsigTimersOnly(bool) { /* TSIG not supported */ }
+func (w *tcpResponseWriter) Hijack()             { /* not supported */ }
+
+// readTCPDNSMessage reads a single DNS message from a TCP connection (length-prefixed).
+func readTCPDNSMessage(conn *gonet.TCPConn) (*dns.Msg, error) {
+	// DNS over TCP uses a 2-byte length prefix
+	lenBuf := make([]byte, 2)
+	if _, err := io.ReadFull(conn, lenBuf); err != nil {
+		return nil, fmt.Errorf("read length: %w", err)
+	}
+
+	msgLen := int(lenBuf[0])<<8 | int(lenBuf[1])
+	if msgLen == 0 || msgLen > 65535 {
+		return nil, fmt.Errorf("invalid message length: %d", msgLen)
+	}
+
+	msgBuf := make([]byte, msgLen)
+	if _, err := io.ReadFull(conn, msgBuf); err != nil {
+		return nil, fmt.Errorf("read message: %w", err)
+	}
+
+	msg := new(dns.Msg)
+	if err := msg.Unpack(msgBuf); err != nil {
+		return nil, fmt.Errorf("unpack: %w", err)
+	}
+	return msg, nil
+}
+
+// srcAddrFromPacket extracts the source IP:port from a raw IP+TCP packet for logging.
+// Supports both IPv4 and IPv6.
+func srcAddrFromPacket(pkt []byte) netip.AddrPort {
+	if len(pkt) == 0 {
+		return netip.AddrPort{}
+	}
+
+	srcIP, transportOffset := srcIPFromPacket(pkt)
+	if !srcIP.IsValid() || len(pkt) < transportOffset+2 {
+		return netip.AddrPort{}
+	}
+
+	srcPort := uint16(pkt[transportOffset])<<8 | uint16(pkt[transportOffset+1])
+	return netip.AddrPortFrom(srcIP.Unmap(), srcPort)
+}
+
+func srcIPFromPacket(pkt []byte) (netip.Addr, int) {
+	switch header.IPVersion(pkt) {
+	case 4:
+		return srcIPv4(pkt)
+	case 6:
+		return srcIPv6(pkt)
+	default:
+		return netip.Addr{}, 0
+	}
+}
+
+func srcIPv4(pkt []byte) (netip.Addr, int) {
+	if len(pkt) < header.IPv4MinimumSize {
+		return netip.Addr{}, 0
+	}
+	hdr := header.IPv4(pkt)
+	src := hdr.SourceAddress()
+	ip, ok := netip.AddrFromSlice(src.AsSlice())
+	if !ok {
+		return netip.Addr{}, 0
+	}
+	return ip, int(hdr.HeaderLength())
+}
+
+func srcIPv6(pkt []byte) (netip.Addr, int) {
+	if len(pkt) < header.IPv6MinimumSize {
+		return netip.Addr{}, 0
+	}
+	hdr := header.IPv6(pkt)
+	src := hdr.SourceAddress()
+	ip, ok := netip.AddrFromSlice(src.AsSlice())
+	if !ok {
+		return netip.Addr{}, 0
+	}
+	return ip, header.IPv6MinimumSize
+}

client/internal/dns/upstream.go

@@ -41,10 +41,61 @@ const (
 
 	reactivatePeriod = 30 * time.Second
 	probeTimeout     = 2 * time.Second
+
+	// ipv6HeaderSize + udpHeaderSize, used to derive the maximum DNS UDP
+	// payload from the tunnel MTU.
+	ipUDPHeaderSize = 60 + 8
 )
 
 const testRecord = "com."
 
+const (
+	protoUDP = "udp"
+	protoTCP = "tcp"
+)
+
+type dnsProtocolKey struct{}
+
+// contextWithDNSProtocol stores the inbound DNS protocol ("udp" or "tcp") in context.
+func contextWithDNSProtocol(ctx context.Context, network string) context.Context {
+	return context.WithValue(ctx, dnsProtocolKey{}, network)
+}
+
+// dnsProtocolFromContext retrieves the inbound DNS protocol from context.
+func dnsProtocolFromContext(ctx context.Context) string {
+	if ctx == nil {
+		return ""
+	}
+	if v, ok := ctx.Value(dnsProtocolKey{}).(string); ok {
+		return v
+	}
+	return ""
+}
+
+type upstreamProtocolKey struct{}
+
+// upstreamProtocolResult holds the protocol used for the upstream exchange.
+// Stored as a pointer in context so the exchange function can set it.
+type upstreamProtocolResult struct {
+	protocol string
+}
+
+// contextWithupstreamProtocolResult stores a mutable result holder in the context.
+func contextWithupstreamProtocolResult(ctx context.Context) (context.Context, *upstreamProtocolResult) {
+	r := &upstreamProtocolResult{}
+	return context.WithValue(ctx, upstreamProtocolKey{}, r), r
+}
+
+// setUpstreamProtocol sets the upstream protocol on the result holder in context, if present.
+func setUpstreamProtocol(ctx context.Context, protocol string) {
+	if ctx == nil {
+		return
+	}
+	if r, ok := ctx.Value(upstreamProtocolKey{}).(*upstreamProtocolResult); ok && r != nil {
+		r.protocol = protocol
+	}
+}
+
 type upstreamClient interface {
 	exchange(ctx context.Context, upstream string, r *dns.Msg) (*dns.Msg, time.Duration, error)
 }
@@ -138,7 +189,16 @@ func (u *upstreamResolverBase) ServeDNS(w dns.ResponseWriter, r *dns.Msg) {
 		return
 	}
 
-	ok, failures := u.tryUpstreamServers(w, r, logger)
+	// Propagate inbound protocol so upstream exchange can use TCP directly
+	// when the request came in over TCP.
+	ctx := u.ctx
+	if addr := w.RemoteAddr(); addr != nil {
+		network := addr.Network()
+		ctx = contextWithDNSProtocol(ctx, network)
+		resutil.SetMeta(w, "protocol", network)
+	}
+
+	ok, failures := u.tryUpstreamServers(ctx, w, r, logger)
 	if len(failures) > 0 {
 		u.logUpstreamFailures(r.Question[0].Name, failures, ok, logger)
 	}
@@ -153,7 +213,7 @@ func (u *upstreamResolverBase) prepareRequest(r *dns.Msg) {
 	}
 }
 
-func (u *upstreamResolverBase) tryUpstreamServers(w dns.ResponseWriter, r *dns.Msg, logger *log.Entry) (bool, []upstreamFailure) {
+func (u *upstreamResolverBase) tryUpstreamServers(ctx context.Context, w dns.ResponseWriter, r *dns.Msg, logger *log.Entry) (bool, []upstreamFailure) {
 	timeout := u.upstreamTimeout
 	if len(u.upstreamServers) > 1 {
 		maxTotal := 5 * time.Second
@@ -168,7 +228,7 @@ func (u *upstreamResolverBase) tryUpstreamServers(w dns.ResponseWriter, r *dns.M
 
 	var failures []upstreamFailure
 	for _, upstream := range u.upstreamServers {
-		if failure := u.queryUpstream(w, r, upstream, timeout, logger); failure != nil {
+		if failure := u.queryUpstream(ctx, w, r, upstream, timeout, logger); failure != nil {
 			failures = append(failures, *failure)
 		} else {
 			return true, failures
@@ -178,15 +238,17 @@ func (u *upstreamResolverBase) tryUpstreamServers(w dns.ResponseWriter, r *dns.M
 }
 
 // queryUpstream queries a single upstream server. Returns nil on success, or failure info to try next upstream.
-func (u *upstreamResolverBase) queryUpstream(w dns.ResponseWriter, r *dns.Msg, upstream netip.AddrPort, timeout time.Duration, logger *log.Entry) *upstreamFailure {
+func (u *upstreamResolverBase) queryUpstream(parentCtx context.Context, w dns.ResponseWriter, r *dns.Msg, upstream netip.AddrPort, timeout time.Duration, logger *log.Entry) *upstreamFailure {
 	var rm *dns.Msg
 	var t time.Duration
 	var err error
 
 	var startTime time.Time
+	var upstreamProto *upstreamProtocolResult
 	func() {
-		ctx, cancel := context.WithTimeout(u.ctx, timeout)
+		ctx, cancel := context.WithTimeout(parentCtx, timeout)
 		defer cancel()
+		ctx, upstreamProto = contextWithupstreamProtocolResult(ctx)
 		startTime = time.Now()
 		rm, t, err = u.upstreamClient.exchange(ctx, upstream.String(), r)
 	}()
@@ -203,7 +265,7 @@ func (u *upstreamResolverBase) queryUpstream(w dns.ResponseWriter, r *dns.Msg, u
 		return &upstreamFailure{upstream: upstream, reason: dns.RcodeToString[rm.Rcode]}
 	}
 
-	u.writeSuccessResponse(w, rm, upstream, r.Question[0].Name, t, logger)
+	u.writeSuccessResponse(w, rm, upstream, r.Question[0].Name, t, upstreamProto, logger)
 	return nil
 }
 
@@ -220,10 +282,13 @@ func (u *upstreamResolverBase) handleUpstreamError(err error, upstream netip.Add
 	return &upstreamFailure{upstream: upstream, reason: reason}
 }
 
-func (u *upstreamResolverBase) writeSuccessResponse(w dns.ResponseWriter, rm *dns.Msg, upstream netip.AddrPort, domain string, t time.Duration, logger *log.Entry) bool {
+func (u *upstreamResolverBase) writeSuccessResponse(w dns.ResponseWriter, rm *dns.Msg, upstream netip.AddrPort, domain string, t time.Duration, upstreamProto *upstreamProtocolResult, logger *log.Entry) bool {
 	u.successCount.Add(1)
 
 	resutil.SetMeta(w, "upstream", upstream.String())
+	if upstreamProto != nil && upstreamProto.protocol != "" {
+		resutil.SetMeta(w, "upstream_protocol", upstreamProto.protocol)
+	}
 
 	// Clear Zero bit from external responses to prevent upstream servers from
 	// manipulating our internal fallthrough signaling mechanism
@@ -428,13 +493,42 @@ func (u *upstreamResolverBase) testNameserver(baseCtx context.Context, externalC
 	return err
 }
 
+// clientUDPMaxSize returns the maximum UDP response size the client accepts.
+func clientUDPMaxSize(r *dns.Msg) int {
+	if opt := r.IsEdns0(); opt != nil {
+		return int(opt.UDPSize())
+	}
+	return dns.MinMsgSize
+}
+
 // ExchangeWithFallback exchanges a DNS message with the upstream server.
 // It first tries to use UDP, and if it is truncated, it falls back to TCP.
+// If the inbound request came over TCP (via context), it skips the UDP attempt.
 // If the passed context is nil, this will use Exchange instead of ExchangeContext.
 func ExchangeWithFallback(ctx context.Context, client *dns.Client, r *dns.Msg, upstream string) (*dns.Msg, time.Duration, error) {
-	// MTU - ip + udp headers
-	// Note: this could be sent out on an interface that is not ours, but higher MTU settings could break truncation handling.
-	client.UDPSize = uint16(currentMTU - (60 + 8))
+	// If the request came in over TCP, go straight to TCP upstream.
+	if dnsProtocolFromContext(ctx) == protoTCP {
+		tcpClient := *client
+		tcpClient.Net = protoTCP
+		rm, t, err := tcpClient.ExchangeContext(ctx, r, upstream)
+		if err != nil {
+			return nil, t, fmt.Errorf("with tcp: %w", err)
+		}
+		setUpstreamProtocol(ctx, protoTCP)
+		return rm, t, nil
+	}
+
+	clientMaxSize := clientUDPMaxSize(r)
+
+	// Cap EDNS0 to our tunnel MTU so the upstream doesn't send a
+	// response larger than our read buffer.
+	// Note: the query could be sent out on an interface that is not ours,
+	// but higher MTU settings could break truncation handling.
+	maxUDPPayload := uint16(currentMTU - ipUDPHeaderSize)
+	client.UDPSize = maxUDPPayload
+	if opt := r.IsEdns0(); opt != nil && opt.UDPSize() > maxUDPPayload {
+		opt.SetUDPSize(maxUDPPayload)
+	}
 
 	var (
 		rm  *dns.Msg
@@ -453,25 +547,32 @@ func ExchangeWithFallback(ctx context.Context, client *dns.Client, r *dns.Msg, u
 	}
 
 	if rm == nil || !rm.MsgHdr.Truncated {
+		setUpstreamProtocol(ctx, protoUDP)
 		return rm, t, nil
 	}
 
-	log.Tracef("udp response for domain=%s type=%v class=%v is truncated, trying TCP.",
-		r.Question[0].Name, r.Question[0].Qtype, r.Question[0].Qclass)
+	// TODO: if the upstream's truncated UDP response already contains more
+	// data than the client's buffer, we could truncate locally and skip
+	// the TCP retry.
 
-	client.Net = "tcp"
+	tcpClient := *client
+	tcpClient.Net = protoTCP
 
 	if ctx == nil {
-		rm, t, err = client.Exchange(r, upstream)
+		rm, t, err = tcpClient.Exchange(r, upstream)
 	} else {
-		rm, t, err = client.ExchangeContext(ctx, r, upstream)
+		rm, t, err = tcpClient.ExchangeContext(ctx, r, upstream)
 	}
 
 	if err != nil {
 		return nil, t, fmt.Errorf("with tcp: %w", err)
 	}
 
-	// TODO: once TCP is implemented, rm.Truncate() if the request came in over UDP
+	setUpstreamProtocol(ctx, protoTCP)
+
+	if rm.Len() > clientMaxSize {
+		rm.Truncate(clientMaxSize)
+	}
 
 	return rm, t, nil
 }
@@ -479,18 +580,46 @@ func ExchangeWithFallback(ctx context.Context, client *dns.Client, r *dns.Msg, u
 // ExchangeWithNetstack performs a DNS exchange using netstack for dialing.
 // This is needed when netstack is enabled to reach peer IPs through the tunnel.
 func ExchangeWithNetstack(ctx context.Context, nsNet *netstack.Net, r *dns.Msg, upstream string) (*dns.Msg, error) {
-	reply, err := netstackExchange(ctx, nsNet, r, upstream, "udp")
+	// If request came in over TCP, go straight to TCP upstream
+	if dnsProtocolFromContext(ctx) == protoTCP {
+		rm, err := netstackExchange(ctx, nsNet, r, upstream, protoTCP)
+		if err != nil {
+			return nil, err
+		}
+		setUpstreamProtocol(ctx, protoTCP)
+		return rm, nil
+	}
+
+	clientMaxSize := clientUDPMaxSize(r)
+
+	// Cap EDNS0 to our tunnel MTU so the upstream doesn't send a
+	// response larger than what we can read over UDP.
+	maxUDPPayload := uint16(currentMTU - ipUDPHeaderSize)
+	if opt := r.IsEdns0(); opt != nil && opt.UDPSize() > maxUDPPayload {
+		opt.SetUDPSize(maxUDPPayload)
+	}
+
+	reply, err := netstackExchange(ctx, nsNet, r, upstream, protoUDP)
 	if err != nil {
 		return nil, err
 	}
 
-	// If response is truncated, retry with TCP
 	if reply != nil && reply.MsgHdr.Truncated {
-		log.Tracef("udp response for domain=%s type=%v class=%v is truncated, trying TCP",
-			r.Question[0].Name, r.Question[0].Qtype, r.Question[0].Qclass)
-		return netstackExchange(ctx, nsNet, r, upstream, "tcp")
+		rm, err := netstackExchange(ctx, nsNet, r, upstream, protoTCP)
+		if err != nil {
+			return nil, err
+		}
+
+		setUpstreamProtocol(ctx, protoTCP)
+		if rm.Len() > clientMaxSize {
+			rm.Truncate(clientMaxSize)
+		}
+
+		return rm, nil
 	}
 
+	setUpstreamProtocol(ctx, protoUDP)
+
 	return reply, nil
 }
 
@@ -511,7 +640,7 @@ func netstackExchange(ctx context.Context, nsNet *netstack.Net, r *dns.Msg, upst
 		}
 	}
 
-	dnsConn := &dns.Conn{Conn: conn}
+	dnsConn := &dns.Conn{Conn: conn, UDPSize: uint16(currentMTU - ipUDPHeaderSize)}
 
 	if err := dnsConn.WriteMsg(r); err != nil {
 		return nil, fmt.Errorf("write %s message: %w", network, err)

client/internal/dns/upstream_android.go

@@ -51,7 +51,7 @@ func (u *upstreamResolver) exchangeWithinVPN(ctx context.Context, upstream strin
 	upstreamExchangeClient := &dns.Client{
 		Timeout: ClientTimeout,
 	}
-	return upstreamExchangeClient.ExchangeContext(ctx, r, upstream)
+	return ExchangeWithFallback(ctx, upstreamExchangeClient, r, upstream)
 }
 
 // exchangeWithoutVPN protect the UDP socket by Android SDK to avoid to goes through the VPN
@@ -76,7 +76,7 @@ func (u *upstreamResolver) exchangeWithoutVPN(ctx context.Context, upstream stri
 		Timeout: timeout,
 	}
 
-	return upstreamExchangeClient.ExchangeContext(ctx, r, upstream)
+	return ExchangeWithFallback(ctx, upstreamExchangeClient, r, upstream)
 }
 
 func (u *upstreamResolver) isLocalResolver(upstream string) bool {

client/internal/dns/upstream_test.go

@@ -475,3 +475,298 @@ func TestFormatFailures(t *testing.T) {
 		})
 	}
 }
+
+func TestDNSProtocolContext(t *testing.T) {
+	t.Run("roundtrip udp", func(t *testing.T) {
+		ctx := contextWithDNSProtocol(context.Background(), protoUDP)
+		assert.Equal(t, protoUDP, dnsProtocolFromContext(ctx))
+	})
+
+	t.Run("roundtrip tcp", func(t *testing.T) {
+		ctx := contextWithDNSProtocol(context.Background(), protoTCP)
+		assert.Equal(t, protoTCP, dnsProtocolFromContext(ctx))
+	})
+
+	t.Run("missing returns empty", func(t *testing.T) {
+		assert.Equal(t, "", dnsProtocolFromContext(context.Background()))
+	})
+}
+
+func TestExchangeWithFallback_TCPContext(t *testing.T) {
+	// Start a local DNS server that responds on TCP only
+	tcpHandler := dns.HandlerFunc(func(w dns.ResponseWriter, r *dns.Msg) {
+		m := new(dns.Msg)
+		m.SetReply(r)
+		m.Answer = append(m.Answer, &dns.A{
+			Hdr: dns.RR_Header{Name: r.Question[0].Name, Rrtype: dns.TypeA, Class: dns.ClassINET, Ttl: 60},
+			A:   net.ParseIP("10.0.0.1"),
+		})
+		if err := w.WriteMsg(m); err != nil {
+			t.Logf("write msg: %v", err)
+		}
+	})
+
+	tcpServer := &dns.Server{
+		Addr:    "127.0.0.1:0",
+		Net:     "tcp",
+		Handler: tcpHandler,
+	}
+
+	tcpLn, err := net.Listen("tcp", "127.0.0.1:0")
+	require.NoError(t, err)
+	tcpServer.Listener = tcpLn
+
+	go func() {
+		if err := tcpServer.ActivateAndServe(); err != nil {
+			t.Logf("tcp server: %v", err)
+		}
+	}()
+	defer func() {
+		_ = tcpServer.Shutdown()
+	}()
+
+	upstream := tcpLn.Addr().String()
+
+	// With TCP context, should connect directly via TCP without trying UDP
+	ctx := contextWithDNSProtocol(context.Background(), protoTCP)
+	client := &dns.Client{Timeout: 2 * time.Second}
+	r := new(dns.Msg).SetQuestion("example.com.", dns.TypeA)
+
+	rm, _, err := ExchangeWithFallback(ctx, client, r, upstream)
+	require.NoError(t, err)
+	require.NotNil(t, rm)
+	require.NotEmpty(t, rm.Answer)
+	assert.Contains(t, rm.Answer[0].String(), "10.0.0.1")
+}
+
+func TestExchangeWithFallback_UDPFallbackToTCP(t *testing.T) {
+	// UDP handler returns a truncated response to trigger TCP retry.
+	udpHandler := dns.HandlerFunc(func(w dns.ResponseWriter, r *dns.Msg) {
+		m := new(dns.Msg)
+		m.SetReply(r)
+		m.Truncated = true
+		if err := w.WriteMsg(m); err != nil {
+			t.Logf("write msg: %v", err)
+		}
+	})
+
+	// TCP handler returns the full answer.
+	tcpHandler := dns.HandlerFunc(func(w dns.ResponseWriter, r *dns.Msg) {
+		m := new(dns.Msg)
+		m.SetReply(r)
+		m.Answer = append(m.Answer, &dns.A{
+			Hdr: dns.RR_Header{Name: r.Question[0].Name, Rrtype: dns.TypeA, Class: dns.ClassINET, Ttl: 60},
+			A:   net.ParseIP("10.0.0.3"),
+		})
+		if err := w.WriteMsg(m); err != nil {
+			t.Logf("write msg: %v", err)
+		}
+	})
+
+	udpPC, err := net.ListenPacket("udp", "127.0.0.1:0")
+	require.NoError(t, err)
+	addr := udpPC.LocalAddr().String()
+
+	udpServer := &dns.Server{
+		PacketConn: udpPC,
+		Net:        "udp",
+		Handler:    udpHandler,
+	}
+
+	tcpLn, err := net.Listen("tcp", addr)
+	require.NoError(t, err)
+
+	tcpServer := &dns.Server{
+		Listener: tcpLn,
+		Net:      "tcp",
+		Handler:  tcpHandler,
+	}
+
+	go func() {
+		if err := udpServer.ActivateAndServe(); err != nil {
+			t.Logf("udp server: %v", err)
+		}
+	}()
+	go func() {
+		if err := tcpServer.ActivateAndServe(); err != nil {
+			t.Logf("tcp server: %v", err)
+		}
+	}()
+	defer func() {
+		_ = udpServer.Shutdown()
+		_ = tcpServer.Shutdown()
+	}()
+
+	ctx := context.Background()
+	client := &dns.Client{Timeout: 2 * time.Second}
+	r := new(dns.Msg).SetQuestion("example.com.", dns.TypeA)
+
+	rm, _, err := ExchangeWithFallback(ctx, client, r, addr)
+	require.NoError(t, err, "should fall back to TCP after truncated UDP response")
+	require.NotNil(t, rm)
+	require.NotEmpty(t, rm.Answer, "TCP response should contain the full answer")
+	assert.Contains(t, rm.Answer[0].String(), "10.0.0.3")
+	assert.False(t, rm.Truncated, "TCP response should not be truncated")
+}
+
+func TestExchangeWithFallback_TCPContextSkipsUDP(t *testing.T) {
+	// Start only a TCP server (no UDP). With TCP context it should succeed.
+	tcpHandler := dns.HandlerFunc(func(w dns.ResponseWriter, r *dns.Msg) {
+		m := new(dns.Msg)
+		m.SetReply(r)
+		m.Answer = append(m.Answer, &dns.A{
+			Hdr: dns.RR_Header{Name: r.Question[0].Name, Rrtype: dns.TypeA, Class: dns.ClassINET, Ttl: 60},
+			A:   net.ParseIP("10.0.0.2"),
+		})
+		if err := w.WriteMsg(m); err != nil {
+			t.Logf("write msg: %v", err)
+		}
+	})
+
+	tcpLn, err := net.Listen("tcp", "127.0.0.1:0")
+	require.NoError(t, err)
+
+	tcpServer := &dns.Server{
+		Listener: tcpLn,
+		Net:      "tcp",
+		Handler:  tcpHandler,
+	}
+
+	go func() {
+		if err := tcpServer.ActivateAndServe(); err != nil {
+			t.Logf("tcp server: %v", err)
+		}
+	}()
+	defer func() {
+		_ = tcpServer.Shutdown()
+	}()
+
+	upstream := tcpLn.Addr().String()
+
+	// TCP context: should skip UDP entirely and go directly to TCP
+	ctx := contextWithDNSProtocol(context.Background(), protoTCP)
+	client := &dns.Client{Timeout: 2 * time.Second}
+	r := new(dns.Msg).SetQuestion("example.com.", dns.TypeA)
+
+	rm, _, err := ExchangeWithFallback(ctx, client, r, upstream)
+	require.NoError(t, err)
+	require.NotNil(t, rm)
+	require.NotEmpty(t, rm.Answer)
+	assert.Contains(t, rm.Answer[0].String(), "10.0.0.2")
+
+	// Without TCP context, trying to reach a TCP-only server via UDP should fail
+	ctx2 := context.Background()
+	client2 := &dns.Client{Timeout: 500 * time.Millisecond}
+	_, _, err = ExchangeWithFallback(ctx2, client2, r, upstream)
+	assert.Error(t, err, "should fail when no UDP server and no TCP context")
+}
+
+func TestExchangeWithFallback_EDNS0Capped(t *testing.T) {
+	// Verify that a client EDNS0 larger than our MTU-derived limit gets
+	// capped in the outgoing request so the upstream doesn't send a
+	// response larger than our read buffer.
+	var receivedUDPSize uint16
+	udpHandler := dns.HandlerFunc(func(w dns.ResponseWriter, r *dns.Msg) {
+		if opt := r.IsEdns0(); opt != nil {
+			receivedUDPSize = opt.UDPSize()
+		}
+		m := new(dns.Msg)
+		m.SetReply(r)
+		m.Answer = append(m.Answer, &dns.A{
+			Hdr: dns.RR_Header{Name: r.Question[0].Name, Rrtype: dns.TypeA, Class: dns.ClassINET, Ttl: 60},
+			A:   net.ParseIP("10.0.0.1"),
+		})
+		if err := w.WriteMsg(m); err != nil {
+			t.Logf("write msg: %v", err)
+		}
+	})
+
+	udpPC, err := net.ListenPacket("udp", "127.0.0.1:0")
+	require.NoError(t, err)
+	addr := udpPC.LocalAddr().String()
+
+	udpServer := &dns.Server{PacketConn: udpPC, Net: "udp", Handler: udpHandler}
+	go func() { _ = udpServer.ActivateAndServe() }()
+	t.Cleanup(func() { _ = udpServer.Shutdown() })
+
+	ctx := context.Background()
+	client := &dns.Client{Timeout: 2 * time.Second}
+	r := new(dns.Msg).SetQuestion("example.com.", dns.TypeA)
+	r.SetEdns0(4096, false)
+
+	rm, _, err := ExchangeWithFallback(ctx, client, r, addr)
+	require.NoError(t, err)
+	require.NotNil(t, rm)
+
+	expectedMax := uint16(currentMTU - ipUDPHeaderSize)
+	assert.Equal(t, expectedMax, receivedUDPSize,
+		"upstream should see capped EDNS0, not the client's 4096")
+}
+
+func TestExchangeWithFallback_TCPTruncatesToClientSize(t *testing.T) {
+	// When the client advertises a large EDNS0 (4096) and the upstream
+	// truncates, the TCP response should NOT be truncated since the full
+	// answer fits within the client's original buffer.
+	udpHandler := dns.HandlerFunc(func(w dns.ResponseWriter, r *dns.Msg) {
+		m := new(dns.Msg)
+		m.SetReply(r)
+		m.Truncated = true
+		if err := w.WriteMsg(m); err != nil {
+			t.Logf("write msg: %v", err)
+		}
+	})
+
+	tcpHandler := dns.HandlerFunc(func(w dns.ResponseWriter, r *dns.Msg) {
+		m := new(dns.Msg)
+		m.SetReply(r)
+		// Add enough records to exceed MTU but fit within 4096
+		for i := range 20 {
+			m.Answer = append(m.Answer, &dns.TXT{
+				Hdr: dns.RR_Header{Name: r.Question[0].Name, Rrtype: dns.TypeTXT, Class: dns.ClassINET, Ttl: 60},
+				Txt: []string{fmt.Sprintf("record-%d-padding-data-to-make-it-longer", i)},
+			})
+		}
+		if err := w.WriteMsg(m); err != nil {
+			t.Logf("write msg: %v", err)
+		}
+	})
+
+	udpPC, err := net.ListenPacket("udp", "127.0.0.1:0")
+	require.NoError(t, err)
+	addr := udpPC.LocalAddr().String()
+
+	udpServer := &dns.Server{PacketConn: udpPC, Net: "udp", Handler: udpHandler}
+	tcpLn, err := net.Listen("tcp", addr)
+	require.NoError(t, err)
+	tcpServer := &dns.Server{Listener: tcpLn, Net: "tcp", Handler: tcpHandler}
+
+	go func() { _ = udpServer.ActivateAndServe() }()
+	go func() { _ = tcpServer.ActivateAndServe() }()
+	t.Cleanup(func() {
+		_ = udpServer.Shutdown()
+		_ = tcpServer.Shutdown()
+	})
+
+	ctx := context.Background()
+	client := &dns.Client{Timeout: 2 * time.Second}
+
+	// Client with large buffer: should get all records without truncation
+	r := new(dns.Msg).SetQuestion("example.com.", dns.TypeTXT)
+	r.SetEdns0(4096, false)
+
+	rm, _, err := ExchangeWithFallback(ctx, client, r, addr)
+	require.NoError(t, err)
+	require.NotNil(t, rm)
+	assert.Len(t, rm.Answer, 20, "large EDNS0 client should get all records")
+	assert.False(t, rm.Truncated, "response should not be truncated for large buffer client")
+
+	// Client with small buffer: should get truncated response
+	r2 := new(dns.Msg).SetQuestion("example.com.", dns.TypeTXT)
+	r2.SetEdns0(512, false)
+
+	rm2, _, err := ExchangeWithFallback(ctx, &dns.Client{Timeout: 2 * time.Second}, r2, addr)
+	require.NoError(t, err)
+	require.NotNil(t, rm2)
+	assert.Less(t, len(rm2.Answer), 20, "small EDNS0 client should get fewer records")
+	assert.True(t, rm2.Truncated, "response should be truncated for small buffer client")
+}

client/internal/dnsfwd/forwarder.go

@@ -237,8 +237,8 @@ func (f *DNSForwarder) writeResponse(logger *log.Entry, w dns.ResponseWriter, re
 		return
 	}
 
-	logger.Tracef("response: domain=%s rcode=%s answers=%s took=%s",
-		qname, dns.RcodeToString[resp.Rcode], resutil.FormatAnswers(resp.Answer), time.Since(startTime))
+	logger.Tracef("response: domain=%s rcode=%s answers=%s size=%dB took=%s",
+		qname, dns.RcodeToString[resp.Rcode], resutil.FormatAnswers(resp.Answer), resp.Len(), time.Since(startTime))
 }
 
 // udpResponseWriter wraps a dns.ResponseWriter to handle UDP-specific truncation.
@@ -263,20 +263,28 @@ func (u *udpResponseWriter) WriteMsg(resp *dns.Msg) error {
 
 func (f *DNSForwarder) handleDNSQueryUDP(w dns.ResponseWriter, query *dns.Msg) {
 	startTime := time.Now()
-	logger := log.WithFields(log.Fields{
+	fields := log.Fields{
 		"request_id": resutil.GenerateRequestID(),
 		"dns_id":     fmt.Sprintf("%04x", query.Id),
-	})
+	}
+	if addr := w.RemoteAddr(); addr != nil {
+		fields["client"] = addr.String()
+	}
+	logger := log.WithFields(fields)
 
 	f.handleDNSQuery(logger, &udpResponseWriter{ResponseWriter: w, query: query}, query, startTime)
 }
 
 func (f *DNSForwarder) handleDNSQueryTCP(w dns.ResponseWriter, query *dns.Msg) {
 	startTime := time.Now()
-	logger := log.WithFields(log.Fields{
+	fields := log.Fields{
 		"request_id": resutil.GenerateRequestID(),
 		"dns_id":     fmt.Sprintf("%04x", query.Id),
-	})
+	}
+	if addr := w.RemoteAddr(); addr != nil {
+		fields["client"] = addr.String()
+	}
+	logger := log.WithFields(fields)
 
 	f.handleDNSQuery(logger, w, query, startTime)
 }

client/internal/engine.go

@@ -46,6 +46,7 @@ import (
 	"github.com/netbirdio/netbird/client/internal/peer/guard"
 	icemaker "github.com/netbirdio/netbird/client/internal/peer/ice"
 	"github.com/netbirdio/netbird/client/internal/peerstore"
+	"github.com/netbirdio/netbird/client/internal/portforward"
 	"github.com/netbirdio/netbird/client/internal/profilemanager"
 	"github.com/netbirdio/netbird/client/internal/relay"
 	"github.com/netbirdio/netbird/client/internal/rosenpass"
@@ -210,9 +211,10 @@ type Engine struct {
 	// checks are the client-applied posture checks that need to be evaluated on the client
 	checks []*mgmProto.Checks
 
-	relayManager *relayClient.Manager
-	stateManager *statemanager.Manager
-	srWatcher    *guard.SRWatcher
+	relayManager       *relayClient.Manager
+	stateManager       *statemanager.Manager
+	portForwardManager *portforward.Manager
+	srWatcher          *guard.SRWatcher
 
 	// Sync response persistence (protected by syncRespMux)
 	syncRespMux         sync.RWMutex
@@ -259,26 +261,27 @@ func NewEngine(
 	mobileDep MobileDependency,
 ) *Engine {
 	engine := &Engine{
-		clientCtx:      clientCtx,
-		clientCancel:   clientCancel,
-		signal:         services.SignalClient,
-		signaler:       peer.NewSignaler(services.SignalClient, config.WgPrivateKey),
-		mgmClient:      services.MgmClient,
-		relayManager:   services.RelayManager,
-		peerStore:      peerstore.NewConnStore(),
-		syncMsgMux:     &sync.Mutex{},
-		config:         config,
-		mobileDep:      mobileDep,
-		STUNs:          []*stun.URI{},
-		TURNs:          []*stun.URI{},
-		networkSerial:  0,
-		statusRecorder: services.StatusRecorder,
-		stateManager:   services.StateManager,
-		checks:         services.Checks,
-		probeStunTurn:  relay.NewStunTurnProbe(relay.DefaultCacheTTL),
-		jobExecutor:    jobexec.NewExecutor(),
-		clientMetrics:  services.ClientMetrics,
-		updateManager:  services.UpdateManager,
+		clientCtx:          clientCtx,
+		clientCancel:       clientCancel,
+		signal:             services.SignalClient,
+		signaler:           peer.NewSignaler(services.SignalClient, config.WgPrivateKey),
+		mgmClient:          services.MgmClient,
+		relayManager:       services.RelayManager,
+		peerStore:          peerstore.NewConnStore(),
+		syncMsgMux:         &sync.Mutex{},
+		config:             config,
+		mobileDep:          mobileDep,
+		STUNs:              []*stun.URI{},
+		TURNs:              []*stun.URI{},
+		networkSerial:      0,
+		statusRecorder:     services.StatusRecorder,
+		stateManager:       services.StateManager,
+		portForwardManager: portforward.NewManager(),
+		checks:             services.Checks,
+		probeStunTurn:      relay.NewStunTurnProbe(relay.DefaultCacheTTL),
+		jobExecutor:        jobexec.NewExecutor(),
+		clientMetrics:      services.ClientMetrics,
+		updateManager:      services.UpdateManager,
 	}
 
 	log.Infof("I am: %s", config.WgPrivateKey.PublicKey().String())
@@ -521,6 +524,11 @@ func (e *Engine) Start(netbirdConfig *mgmProto.NetbirdConfig, mgmtURL *url.URL)
 		return err
 	}
 
+	// Inject firewall into DNS server now that it's available.
+	// The DNS server is created before the firewall because the route manager
+	// depends on the DNS server, and the firewall depends on the wg interface.
+	e.dnsServer.SetFirewall(e.firewall)
+
 	e.udpMux, err = e.wgInterface.Up()
 	if err != nil {
 		log.Errorf("failed to pull up wgInterface [%s]: %s", e.wgInterface.Name(), err.Error())
@@ -532,6 +540,13 @@ func (e *Engine) Start(netbirdConfig *mgmProto.NetbirdConfig, mgmtURL *url.URL)
 	// conntrack entries from being created before the rules are in place
 	e.setupWGProxyNoTrack()
 
+	// Start after interface is up since port may have been resolved from 0 or changed if occupied
+	e.shutdownWg.Add(1)
+	go func() {
+		defer e.shutdownWg.Done()
+		e.portForwardManager.Start(e.ctx, uint16(e.config.WgPort))
+	}()
+
 	// Set the WireGuard interface for rosenpass after interface is up
 	if e.rpManager != nil {
 		e.rpManager.SetInterface(e.wgInterface)
@@ -1535,12 +1550,13 @@ func (e *Engine) createPeerConn(pubKey string, allowedIPs []netip.Prefix, agentV
 	}
 
 	serviceDependencies := peer.ServiceDependencies{
-		StatusRecorder:  e.statusRecorder,
-		Signaler:        e.signaler,
-		IFaceDiscover:   e.mobileDep.IFaceDiscover,
-		RelayManager:    e.relayManager,
-		SrWatcher:       e.srWatcher,
-		MetricsRecorder: e.clientMetrics,
+		StatusRecorder:     e.statusRecorder,
+		Signaler:           e.signaler,
+		IFaceDiscover:      e.mobileDep.IFaceDiscover,
+		RelayManager:       e.relayManager,
+		SrWatcher:          e.srWatcher,
+		PortForwardManager: e.portForwardManager,
+		MetricsRecorder:    e.clientMetrics,
 	}
 	peerConn, err := peer.NewConn(config, serviceDependencies)
 	if err != nil {
@@ -1697,6 +1713,12 @@ func (e *Engine) close() {
 	if e.rpManager != nil {
 		_ = e.rpManager.Close()
 	}
+
+	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
+	defer cancel()
+	if err := e.portForwardManager.GracefullyStop(ctx); err != nil {
+		log.Warnf("failed to gracefully stop port forwarding manager: %s", err)
+	}
 }
 
 func (e *Engine) readInitialSettings() ([]*route.Route, *nbdns.Config, bool, error) {
@@ -1800,7 +1822,7 @@ func (e *Engine) newDnsServer(dnsConfig *nbdns.Config) (dns.Server, error) {
 		return dnsServer, nil
 
 	case "ios":
-		dnsServer := dns.NewDefaultServerIos(e.ctx, e.wgInterface, e.mobileDep.DnsManager, e.statusRecorder, e.config.DisableDNS)
+		dnsServer := dns.NewDefaultServerIos(e.ctx, e.wgInterface, e.mobileDep.DnsManager, e.mobileDep.HostDNSAddresses, e.statusRecorder, e.config.DisableDNS)
 		return dnsServer, nil
 
 	default:
@@ -1837,6 +1859,11 @@ func (e *Engine) GetExposeManager() *expose.Manager {
 	return e.exposeManager
 }
 
+// IsBlockInbound returns whether inbound connections are blocked.
+func (e *Engine) IsBlockInbound() bool {
+	return e.config.BlockInbound
+}
+
 // GetClientMetrics returns the client metrics
 func (e *Engine) GetClientMetrics() *metrics.ClientMetrics {
 	return e.clientMetrics

client/internal/peer/conn.go

@@ -22,6 +22,7 @@ import (
 	icemaker "github.com/netbirdio/netbird/client/internal/peer/ice"
 	"github.com/netbirdio/netbird/client/internal/peer/id"
 	"github.com/netbirdio/netbird/client/internal/peer/worker"
+	"github.com/netbirdio/netbird/client/internal/portforward"
 	"github.com/netbirdio/netbird/client/internal/stdnet"
 	"github.com/netbirdio/netbird/route"
 	relayClient "github.com/netbirdio/netbird/shared/relay/client"
@@ -45,6 +46,7 @@ type ServiceDependencies struct {
 	RelayManager       *relayClient.Manager
 	SrWatcher          *guard.SRWatcher
 	PeerConnDispatcher *dispatcher.ConnectionDispatcher
+	PortForwardManager *portforward.Manager
 	MetricsRecorder    MetricsRecorder
 }
 
@@ -87,16 +89,17 @@ type ConnConfig struct {
 }
 
 type Conn struct {
-	Log            *log.Entry
-	mu             sync.Mutex
-	ctx            context.Context
-	ctxCancel      context.CancelFunc
-	config         ConnConfig
-	statusRecorder *Status
-	signaler       *Signaler
-	iFaceDiscover  stdnet.ExternalIFaceDiscover
-	relayManager   *relayClient.Manager
-	srWatcher      *guard.SRWatcher
+	Log                *log.Entry
+	mu                 sync.Mutex
+	ctx                context.Context
+	ctxCancel          context.CancelFunc
+	config             ConnConfig
+	statusRecorder     *Status
+	signaler           *Signaler
+	iFaceDiscover      stdnet.ExternalIFaceDiscover
+	relayManager       *relayClient.Manager
+	srWatcher          *guard.SRWatcher
+	portForwardManager *portforward.Manager
 
 	onConnected                               func(remoteWireGuardKey string, remoteRosenpassPubKey []byte, wireGuardIP string, remoteRosenpassAddr string)
 	onDisconnected                            func(remotePeer string)
@@ -145,19 +148,20 @@ func NewConn(config ConnConfig, services ServiceDependencies) (*Conn, error) {
 
 	dumpState := newStateDump(config.Key, connLog, services.StatusRecorder)
 	var conn = &Conn{
-		Log:             connLog,
-		config:          config,
-		statusRecorder:  services.StatusRecorder,
-		signaler:        services.Signaler,
-		iFaceDiscover:   services.IFaceDiscover,
-		relayManager:    services.RelayManager,
-		srWatcher:       services.SrWatcher,
-		statusRelay:     worker.NewAtomicStatus(),
-		statusICE:       worker.NewAtomicStatus(),
-		dumpState:       dumpState,
-		endpointUpdater: NewEndpointUpdater(connLog, config.WgConfig, isController(config)),
-		wgWatcher:       NewWGWatcher(connLog, config.WgConfig.WgInterface, config.Key, dumpState),
-		metricsRecorder: services.MetricsRecorder,
+		Log:                connLog,
+		config:             config,
+		statusRecorder:     services.StatusRecorder,
+		signaler:           services.Signaler,
+		iFaceDiscover:      services.IFaceDiscover,
+		relayManager:       services.RelayManager,
+		srWatcher:          services.SrWatcher,
+		portForwardManager: services.PortForwardManager,
+		statusRelay:        worker.NewAtomicStatus(),
+		statusICE:          worker.NewAtomicStatus(),
+		dumpState:          dumpState,
+		endpointUpdater:    NewEndpointUpdater(connLog, config.WgConfig, isController(config)),
+		wgWatcher:          NewWGWatcher(connLog, config.WgConfig.WgInterface, config.Key, dumpState),
+		metricsRecorder:    services.MetricsRecorder,
 	}
 
 	return conn, nil

client/internal/peer/worker_ice.go

@@ -16,6 +16,7 @@ import (
 	"github.com/netbirdio/netbird/client/iface/udpmux"
 	"github.com/netbirdio/netbird/client/internal/peer/conntype"
 	icemaker "github.com/netbirdio/netbird/client/internal/peer/ice"
+	"github.com/netbirdio/netbird/client/internal/portforward"
 	"github.com/netbirdio/netbird/client/internal/stdnet"
 	"github.com/netbirdio/netbird/route"
 )
@@ -61,6 +62,9 @@ type WorkerICE struct {
 
 	// we record the last known state of the ICE agent to avoid duplicate on disconnected events
 	lastKnownState ice.ConnectionState
+
+	// portForwardAttempted tracks if we've already tried port forwarding this session
+	portForwardAttempted bool
 }
 
 func NewWorkerICE(ctx context.Context, log *log.Entry, config ConnConfig, conn *Conn, signaler *Signaler, ifaceDiscover stdnet.ExternalIFaceDiscover, statusRecorder *Status, hasRelayOnLocally bool) (*WorkerICE, error) {
@@ -214,6 +218,8 @@ func (w *WorkerICE) Close() {
 }
 
 func (w *WorkerICE) reCreateAgent(dialerCancel context.CancelFunc, candidates []ice.CandidateType) (*icemaker.ThreadSafeAgent, error) {
+	w.portForwardAttempted = false
+
 	agent, err := icemaker.NewAgent(w.ctx, w.iFaceDiscover, w.config.ICEConfig, candidates, w.localUfrag, w.localPwd)
 	if err != nil {
 		return nil, fmt.Errorf("create agent: %w", err)
@@ -370,6 +376,93 @@ func (w *WorkerICE) onICECandidate(candidate ice.Candidate) {
 			w.log.Errorf("failed signaling candidate to the remote peer %s %s", w.config.Key, err)
 		}
 	}()
+
+	if candidate.Type() == ice.CandidateTypeServerReflexive {
+		w.injectPortForwardedCandidate(candidate)
+	}
+}
+
+// injectPortForwardedCandidate signals an additional candidate using the pre-created port mapping.
+func (w *WorkerICE) injectPortForwardedCandidate(srflxCandidate ice.Candidate) {
+	pfManager := w.conn.portForwardManager
+	if pfManager == nil {
+		return
+	}
+
+	mapping := pfManager.GetMapping()
+	if mapping == nil {
+		return
+	}
+
+	w.muxAgent.Lock()
+	if w.portForwardAttempted {
+		w.muxAgent.Unlock()
+		return
+	}
+	w.portForwardAttempted = true
+	w.muxAgent.Unlock()
+
+	forwardedCandidate, err := w.createForwardedCandidate(srflxCandidate, mapping)
+	if err != nil {
+		w.log.Warnf("create forwarded candidate: %v", err)
+		return
+	}
+
+	w.log.Debugf("injecting port-forwarded candidate: %s (mapping: %d -> %d via %s, priority: %d)",
+		forwardedCandidate.String(), mapping.InternalPort, mapping.ExternalPort, mapping.NATType, forwardedCandidate.Priority())
+
+	go func() {
+		if err := w.signaler.SignalICECandidate(forwardedCandidate, w.config.Key); err != nil {
+			w.log.Errorf("signal port-forwarded candidate: %v", err)
+		}
+	}()
+}
+
+// createForwardedCandidate creates a new server reflexive candidate with the forwarded port.
+// It uses the NAT gateway's external IP with the forwarded port.
+func (w *WorkerICE) createForwardedCandidate(srflxCandidate ice.Candidate, mapping *portforward.Mapping) (ice.Candidate, error) {
+	var externalIP string
+	if mapping.ExternalIP != nil && !mapping.ExternalIP.IsUnspecified() {
+		externalIP = mapping.ExternalIP.String()
+	} else {
+		// Fallback to STUN-discovered address if NAT didn't provide external IP
+		externalIP = srflxCandidate.Address()
+	}
+
+	// Per RFC 8445, the related address for srflx is the base (host candidate address).
+	// If the original srflx has unspecified related address, use its own address as base.
+	relAddr := srflxCandidate.RelatedAddress().Address
+	if relAddr == "" || relAddr == "0.0.0.0" || relAddr == "::" {
+		relAddr = srflxCandidate.Address()
+	}
+
+	// Arbitrary +1000 boost on top of RFC 8445 priority to favor port-forwarded candidates
+	// over regular srflx during ICE connectivity checks.
+	priority := srflxCandidate.Priority() + 1000
+
+	candidate, err := ice.NewCandidateServerReflexive(&ice.CandidateServerReflexiveConfig{
+		Network:   srflxCandidate.NetworkType().String(),
+		Address:   externalIP,
+		Port:      int(mapping.ExternalPort),
+		Component: srflxCandidate.Component(),
+		Priority:  priority,
+		RelAddr:   relAddr,
+		RelPort:   int(mapping.InternalPort),
+	})
+	if err != nil {
+		return nil, fmt.Errorf("create candidate: %w", err)
+	}
+
+	for _, e := range srflxCandidate.Extensions() {
+		if e.Key == ice.ExtensionKeyCandidateID {
+			e.Value = srflxCandidate.ID()
+		}
+		if err := candidate.AddExtension(e); err != nil {
+			return nil, fmt.Errorf("add extension: %w", err)
+		}
+	}
+
+	return candidate, nil
 }
 
 func (w *WorkerICE) onICESelectedCandidatePair(agent *icemaker.ThreadSafeAgent, c1, c2 ice.Candidate) {
@@ -411,10 +504,10 @@ func (w *WorkerICE) logSuccessfulPaths(agent *icemaker.ThreadSafeAgent) {
 			if !lok || !rok {
 				continue
 			}
-			w.log.Debugf("successful ICE path %s: [%s %s %s] <-> [%s %s %s] rtt=%.3fms",
+			w.log.Debugf("successful ICE path %s: [%s %s %s:%d] <-> [%s %s %s:%d] rtt=%.3fms",
 				sessionID,
-				local.NetworkType(), local.Type(), local.Address(),
-				remote.NetworkType(), remote.Type(), remote.Address(),
+				local.NetworkType(), local.Type(), local.Address(), local.Port(),
+				remote.NetworkType(), remote.Type(), remote.Address(), remote.Port(),
 				stat.CurrentRoundTripTime*1000)
 		}
 	}

client/internal/portforward/env.go

@@ -0,0 +1,35 @@
+package portforward
+
+import (
+	"os"
+	"strconv"
+
+	log "github.com/sirupsen/logrus"
+)
+
+const (
+	envDisableNATMapper      = "NB_DISABLE_NAT_MAPPER"
+	envDisablePCPHealthCheck = "NB_DISABLE_PCP_HEALTH_CHECK"
+)
+
+func isDisabledByEnv() bool {
+	return parseBoolEnv(envDisableNATMapper)
+}
+
+func isHealthCheckDisabled() bool {
+	return parseBoolEnv(envDisablePCPHealthCheck)
+}
+
+func parseBoolEnv(key string) bool {
+	val := os.Getenv(key)
+	if val == "" {
+		return false
+	}
+
+	disabled, err := strconv.ParseBool(val)
+	if err != nil {
+		log.Warnf("failed to parse %s: %v", key, err)
+		return false
+	}
+	return disabled
+}

client/internal/portforward/manager.go

@@ -0,0 +1,342 @@
+//go:build !js
+
+package portforward
+
+import (
+	"context"
+	"fmt"
+	"net"
+	"regexp"
+	"sync"
+	"time"
+
+	"github.com/libp2p/go-nat"
+	log "github.com/sirupsen/logrus"
+
+	"github.com/netbirdio/netbird/client/internal/portforward/pcp"
+)
+
+const (
+	defaultMappingTTL   = 2 * time.Hour
+	healthCheckInterval = 1 * time.Minute
+	discoveryTimeout    = 10 * time.Second
+	mappingDescription  = "NetBird"
+)
+
+// upnpErrPermanentLeaseOnly matches UPnP error 725 in SOAP fault XML,
+// allowing for whitespace/newlines between tags from different router firmware.
+var upnpErrPermanentLeaseOnly = regexp.MustCompile(`<errorCode>\s*725\s*</errorCode>`)
+
+// Mapping represents an active NAT port mapping.
+type Mapping struct {
+	Protocol     string
+	InternalPort uint16
+	ExternalPort uint16
+	ExternalIP   net.IP
+	NATType      string
+	// TTL is the lease duration. Zero means a permanent lease that never expires.
+	TTL time.Duration
+}
+
+// TODO: persist mapping state for crash recovery cleanup of permanent leases.
+// Currently not done because State.Cleanup requires NAT gateway re-discovery,
+// which blocks startup for ~10s when no gateway is present (affects all clients).
+
+type Manager struct {
+	cancel context.CancelFunc
+
+	mapping     *Mapping
+	mappingLock sync.Mutex
+
+	wgPort uint16
+
+	done    chan struct{}
+	stopCtx chan context.Context
+
+	// protect exported functions
+	mu sync.Mutex
+}
+
+// NewManager creates a new port forwarding manager.
+func NewManager() *Manager {
+	return &Manager{
+		stopCtx: make(chan context.Context, 1),
+	}
+}
+
+func (m *Manager) Start(ctx context.Context, wgPort uint16) {
+	m.mu.Lock()
+	if m.cancel != nil {
+		m.mu.Unlock()
+		return
+	}
+
+	if isDisabledByEnv() {
+		log.Infof("NAT port mapper disabled via %s", envDisableNATMapper)
+		m.mu.Unlock()
+		return
+	}
+
+	if wgPort == 0 {
+		log.Warnf("invalid WireGuard port 0; NAT mapping disabled")
+		m.mu.Unlock()
+		return
+	}
+	m.wgPort = wgPort
+
+	m.done = make(chan struct{})
+	defer close(m.done)
+
+	ctx, m.cancel = context.WithCancel(ctx)
+	m.mu.Unlock()
+
+	gateway, mapping, err := m.setup(ctx)
+	if err != nil {
+		log.Infof("port forwarding setup: %v", err)
+		return
+	}
+
+	m.mappingLock.Lock()
+	m.mapping = mapping
+	m.mappingLock.Unlock()
+
+	m.renewLoop(ctx, gateway, mapping.TTL)
+
+	select {
+	case cleanupCtx := <-m.stopCtx:
+		// block the Start while cleaned up gracefully
+		m.cleanup(cleanupCtx, gateway)
+	default:
+		// return Start immediately and cleanup in background
+		cleanupCtx, cleanupCancel := context.WithTimeout(context.Background(), 10*time.Second)
+		go func() {
+			defer cleanupCancel()
+			m.cleanup(cleanupCtx, gateway)
+		}()
+	}
+}
+
+// GetMapping returns the current mapping if ready, nil otherwise
+func (m *Manager) GetMapping() *Mapping {
+	m.mappingLock.Lock()
+	defer m.mappingLock.Unlock()
+
+	if m.mapping == nil {
+		return nil
+	}
+
+	mapping := *m.mapping
+	return &mapping
+}
+
+// GracefullyStop cancels the manager and attempts to delete the port mapping.
+// After GracefullyStop returns, the manager cannot be restarted.
+func (m *Manager) GracefullyStop(ctx context.Context) error {
+	m.mu.Lock()
+	defer m.mu.Unlock()
+
+	if m.cancel == nil {
+		return nil
+	}
+
+	// Send cleanup context before cancelling, so Start picks it up after renewLoop exits.
+	m.startTearDown(ctx)
+
+	m.cancel()
+	m.cancel = nil
+
+	select {
+	case <-ctx.Done():
+		return ctx.Err()
+	case <-m.done:
+		return nil
+	}
+}
+
+func (m *Manager) setup(ctx context.Context) (nat.NAT, *Mapping, error) {
+	discoverCtx, discoverCancel := context.WithTimeout(ctx, discoveryTimeout)
+	defer discoverCancel()
+
+	gateway, err := discoverGateway(discoverCtx)
+	if err != nil {
+		return nil, nil, fmt.Errorf("discover gateway: %w", err)
+	}
+
+	log.Infof("discovered NAT gateway: %s", gateway.Type())
+
+	mapping, err := m.createMapping(ctx, gateway)
+	if err != nil {
+		return nil, nil, fmt.Errorf("create port mapping: %w", err)
+	}
+	return gateway, mapping, nil
+}
+
+func (m *Manager) createMapping(ctx context.Context, gateway nat.NAT) (*Mapping, error) {
+	ctx, cancel := context.WithTimeout(ctx, 30*time.Second)
+	defer cancel()
+
+	ttl := defaultMappingTTL
+	externalPort, err := gateway.AddPortMapping(ctx, "udp", int(m.wgPort), mappingDescription, ttl)
+	if err != nil {
+		if !isPermanentLeaseRequired(err) {
+			return nil, err
+		}
+		log.Infof("gateway only supports permanent leases, retrying with indefinite duration")
+		ttl = 0
+		externalPort, err = gateway.AddPortMapping(ctx, "udp", int(m.wgPort), mappingDescription, ttl)
+		if err != nil {
+			return nil, err
+		}
+	}
+
+	externalIP, err := gateway.GetExternalAddress()
+	if err != nil {
+		log.Debugf("failed to get external address: %v", err)
+	}
+
+	mapping := &Mapping{
+		Protocol:     "udp",
+		InternalPort: m.wgPort,
+		ExternalPort: uint16(externalPort),
+		ExternalIP:   externalIP,
+		NATType:      gateway.Type(),
+		TTL:          ttl,
+	}
+
+	log.Infof("created port mapping: %d -> %d via %s (external IP: %s)",
+		m.wgPort, externalPort, gateway.Type(), externalIP)
+	return mapping, nil
+}
+
+func (m *Manager) renewLoop(ctx context.Context, gateway nat.NAT, ttl time.Duration) {
+	if ttl == 0 {
+		// Permanent mappings don't expire, just wait for cancellation
+		// but still run health checks for PCP gateways.
+		m.permanentLeaseLoop(ctx, gateway)
+		return
+	}
+
+	renewTicker := time.NewTicker(ttl / 2)
+	healthTicker := time.NewTicker(healthCheckInterval)
+	defer renewTicker.Stop()
+	defer healthTicker.Stop()
+
+	for {
+		select {
+		case <-ctx.Done():
+			return
+		case <-renewTicker.C:
+			if err := m.renewMapping(ctx, gateway); err != nil {
+				log.Warnf("failed to renew port mapping: %v", err)
+				continue
+			}
+		case <-healthTicker.C:
+			if m.checkHealthAndRecreate(ctx, gateway) {
+				renewTicker.Reset(ttl / 2)
+			}
+		}
+	}
+}
+
+func (m *Manager) permanentLeaseLoop(ctx context.Context, gateway nat.NAT) {
+	healthTicker := time.NewTicker(healthCheckInterval)
+	defer healthTicker.Stop()
+
+	for {
+		select {
+		case <-ctx.Done():
+			return
+		case <-healthTicker.C:
+			m.checkHealthAndRecreate(ctx, gateway)
+		}
+	}
+}
+
+func (m *Manager) checkHealthAndRecreate(ctx context.Context, gateway nat.NAT) bool {
+	if isHealthCheckDisabled() {
+		return false
+	}
+
+	m.mappingLock.Lock()
+	hasMapping := m.mapping != nil
+	m.mappingLock.Unlock()
+
+	if !hasMapping {
+		return false
+	}
+
+	pcpNAT, ok := gateway.(*pcp.NAT)
+	if !ok {
+		return false
+	}
+
+	ctx, cancel := context.WithTimeout(ctx, 10*time.Second)
+	defer cancel()
+
+	epoch, serverRestarted, err := pcpNAT.CheckServerHealth(ctx)
+	if err != nil {
+		log.Debugf("PCP health check failed: %v", err)
+		return false
+	}
+
+	if serverRestarted {
+		log.Warnf("PCP server restart detected (epoch=%d), recreating port mapping", epoch)
+		if err := m.renewMapping(ctx, gateway); err != nil {
+			log.Errorf("failed to recreate port mapping after server restart: %v", err)
+			return false
+		}
+		return true
+	}
+
+	return false
+}
+
+func (m *Manager) renewMapping(ctx context.Context, gateway nat.NAT) error {
+	ctx, cancel := context.WithTimeout(ctx, 30*time.Second)
+	defer cancel()
+
+	externalPort, err := gateway.AddPortMapping(ctx, m.mapping.Protocol, int(m.mapping.InternalPort), mappingDescription, m.mapping.TTL)
+	if err != nil {
+		return fmt.Errorf("add port mapping: %w", err)
+	}
+
+	if uint16(externalPort) != m.mapping.ExternalPort {
+		log.Warnf("external port changed on renewal: %d -> %d (candidate may be stale)", m.mapping.ExternalPort, externalPort)
+		m.mappingLock.Lock()
+		m.mapping.ExternalPort = uint16(externalPort)
+		m.mappingLock.Unlock()
+	}
+
+	log.Debugf("renewed port mapping: %d -> %d", m.mapping.InternalPort, m.mapping.ExternalPort)
+	return nil
+}
+
+func (m *Manager) cleanup(ctx context.Context, gateway nat.NAT) {
+	m.mappingLock.Lock()
+	mapping := m.mapping
+	m.mapping = nil
+	m.mappingLock.Unlock()
+
+	if mapping == nil {
+		return
+	}
+
+	if err := gateway.DeletePortMapping(ctx, mapping.Protocol, int(mapping.InternalPort)); err != nil {
+		log.Warnf("delete port mapping on stop: %v", err)
+		return
+	}
+
+	log.Infof("deleted port mapping for port %d", mapping.InternalPort)
+}
+
+func (m *Manager) startTearDown(ctx context.Context) {
+	select {
+	case m.stopCtx <- ctx:
+	default:
+	}
+}
+
+// isPermanentLeaseRequired checks if a UPnP error indicates the gateway only supports permanent leases (error 725).
+func isPermanentLeaseRequired(err error) bool {
+	return err != nil && upnpErrPermanentLeaseOnly.MatchString(err.Error())
+}

client/internal/portforward/manager_js.go

@@ -0,0 +1,39 @@
+package portforward
+
+import (
+	"context"
+	"net"
+	"time"
+)
+
+// Mapping represents an active NAT port mapping.
+type Mapping struct {
+	Protocol     string
+	InternalPort uint16
+	ExternalPort uint16
+	ExternalIP   net.IP
+	NATType      string
+	// TTL is the lease duration. Zero means a permanent lease that never expires.
+	TTL time.Duration
+}
+
+// Manager is a stub for js/wasm builds where NAT-PMP/UPnP is not supported.
+type Manager struct{}
+
+// NewManager returns a stub manager for js/wasm builds.
+func NewManager() *Manager {
+	return &Manager{}
+}
+
+// Start is a no-op on js/wasm: NAT-PMP/UPnP is not available in browser environments.
+func (m *Manager) Start(context.Context, uint16) {
+	// no NAT traversal in wasm
+}
+
+// GracefullyStop is a no-op on js/wasm.
+func (m *Manager) GracefullyStop(context.Context) error { return nil }
+
+// GetMapping always returns nil on js/wasm.
+func (m *Manager) GetMapping() *Mapping {
+	return nil
+}

client/internal/portforward/manager_test.go

@@ -0,0 +1,201 @@
+//go:build !js
+
+package portforward
+
+import (
+	"context"
+	"fmt"
+	"net"
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+type mockNAT struct {
+	natType             string
+	deviceAddr          net.IP
+	externalAddr        net.IP
+	internalAddr        net.IP
+	mappings            map[int]int
+	addMappingErr       error
+	deleteMappingErr    error
+	onlyPermanentLeases bool
+	lastTimeout         time.Duration
+}
+
+func newMockNAT() *mockNAT {
+	return &mockNAT{
+		natType:      "Mock-NAT",
+		deviceAddr:   net.ParseIP("192.168.1.1"),
+		externalAddr: net.ParseIP("203.0.113.50"),
+		internalAddr: net.ParseIP("192.168.1.100"),
+		mappings:     make(map[int]int),
+	}
+}
+
+func (m *mockNAT) Type() string {
+	return m.natType
+}
+
+func (m *mockNAT) GetDeviceAddress() (net.IP, error) {
+	return m.deviceAddr, nil
+}
+
+func (m *mockNAT) GetExternalAddress() (net.IP, error) {
+	return m.externalAddr, nil
+}
+
+func (m *mockNAT) GetInternalAddress() (net.IP, error) {
+	return m.internalAddr, nil
+}
+
+func (m *mockNAT) AddPortMapping(ctx context.Context, protocol string, internalPort int, description string, timeout time.Duration) (int, error) {
+	if m.addMappingErr != nil {
+		return 0, m.addMappingErr
+	}
+	if m.onlyPermanentLeases && timeout != 0 {
+		return 0, fmt.Errorf("SOAP fault. Code:  | Explanation:  | Detail: <UPnPError xmlns=\"urn:schemas-upnp-org:control-1-0\"><errorCode>725</errorCode><errorDescription>OnlyPermanentLeasesSupported</errorDescription></UPnPError>")
+	}
+	externalPort := internalPort
+	m.mappings[internalPort] = externalPort
+	m.lastTimeout = timeout
+	return externalPort, nil
+}
+
+func (m *mockNAT) DeletePortMapping(ctx context.Context, protocol string, internalPort int) error {
+	if m.deleteMappingErr != nil {
+		return m.deleteMappingErr
+	}
+	delete(m.mappings, internalPort)
+	return nil
+}
+
+func TestManager_CreateMapping(t *testing.T) {
+	m := NewManager()
+	m.wgPort = 51820
+
+	gateway := newMockNAT()
+	mapping, err := m.createMapping(context.Background(), gateway)
+	require.NoError(t, err)
+	require.NotNil(t, mapping)
+
+	assert.Equal(t, "udp", mapping.Protocol)
+	assert.Equal(t, uint16(51820), mapping.InternalPort)
+	assert.Equal(t, uint16(51820), mapping.ExternalPort)
+	assert.Equal(t, "Mock-NAT", mapping.NATType)
+	assert.Equal(t, net.ParseIP("203.0.113.50").To4(), mapping.ExternalIP.To4())
+	assert.Equal(t, defaultMappingTTL, mapping.TTL)
+}
+
+func TestManager_GetMapping_ReturnsNilWhenNotReady(t *testing.T) {
+	m := NewManager()
+	assert.Nil(t, m.GetMapping())
+}
+
+func TestManager_GetMapping_ReturnsCopy(t *testing.T) {
+	m := NewManager()
+	m.mapping = &Mapping{
+		Protocol:     "udp",
+		InternalPort: 51820,
+		ExternalPort: 51820,
+	}
+
+	mapping := m.GetMapping()
+	require.NotNil(t, mapping)
+	assert.Equal(t, uint16(51820), mapping.InternalPort)
+
+	// Mutating the returned copy should not affect the manager's mapping.
+	mapping.ExternalPort = 9999
+	assert.Equal(t, uint16(51820), m.GetMapping().ExternalPort)
+}
+
+func TestManager_Cleanup_DeletesMapping(t *testing.T) {
+	m := NewManager()
+	m.mapping = &Mapping{
+		Protocol:     "udp",
+		InternalPort: 51820,
+		ExternalPort: 51820,
+	}
+
+	gateway := newMockNAT()
+	// Seed the mock so we can verify deletion.
+	gateway.mappings[51820] = 51820
+
+	m.cleanup(context.Background(), gateway)
+
+	_, exists := gateway.mappings[51820]
+	assert.False(t, exists, "mapping should be deleted from gateway")
+	assert.Nil(t, m.GetMapping(), "in-memory mapping should be cleared")
+}
+
+func TestManager_Cleanup_NilMapping(t *testing.T) {
+	m := NewManager()
+	gateway := newMockNAT()
+
+	// Should not panic or call gateway.
+	m.cleanup(context.Background(), gateway)
+}
+
+
+func TestManager_CreateMapping_PermanentLeaseFallback(t *testing.T) {
+	m := NewManager()
+	m.wgPort = 51820
+
+	gateway := newMockNAT()
+	gateway.onlyPermanentLeases = true
+
+	mapping, err := m.createMapping(context.Background(), gateway)
+	require.NoError(t, err)
+	require.NotNil(t, mapping)
+
+	assert.Equal(t, uint16(51820), mapping.InternalPort)
+	assert.Equal(t, time.Duration(0), mapping.TTL, "should return zero TTL for permanent lease")
+	assert.Equal(t, time.Duration(0), gateway.lastTimeout, "should have retried with zero duration")
+}
+
+func TestIsPermanentLeaseRequired(t *testing.T) {
+	tests := []struct {
+		name     string
+		err      error
+		expected bool
+	}{
+		{
+			name:     "nil error",
+			err:      nil,
+			expected: false,
+		},
+		{
+			name:     "UPnP error 725",
+			err:      fmt.Errorf("SOAP fault. Code:  | Detail: <UPnPError><errorCode>725</errorCode><errorDescription>OnlyPermanentLeasesSupported</errorDescription></UPnPError>"),
+			expected: true,
+		},
+		{
+			name:     "wrapped error with 725",
+			err:      fmt.Errorf("add port mapping: %w", fmt.Errorf("Detail: <errorCode>725</errorCode>")),
+			expected: true,
+		},
+		{
+			name:     "error 725 with newlines in XML",
+			err:      fmt.Errorf("<errorCode>\n  725\n</errorCode>"),
+			expected: true,
+		},
+		{
+			name:     "bare 725 without XML tag",
+			err:      fmt.Errorf("error code 725"),
+			expected: false,
+		},
+		{
+			name:     "unrelated error",
+			err:      fmt.Errorf("connection refused"),
+			expected: false,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			assert.Equal(t, tt.expected, isPermanentLeaseRequired(tt.err))
+		})
+	}
+}

client/internal/portforward/pcp/client.go

@@ -0,0 +1,408 @@
+package pcp
+
+import (
+	"context"
+	"crypto/rand"
+	"errors"
+	"fmt"
+	"net"
+	"net/netip"
+	"sync"
+	"time"
+
+	log "github.com/sirupsen/logrus"
+)
+
+const (
+	defaultTimeout     = 3 * time.Second
+	responseBufferSize = 128
+
+	// RFC 6887 Section 8.1.1 retry timing
+	initialRetryDelay = 3 * time.Second
+	maxRetryDelay     = 1024 * time.Second
+	maxRetries        = 4 // 3s + 6s + 12s + 24s = 45s total worst case
+)
+
+// Client is a PCP protocol client.
+// All methods are safe for concurrent use.
+type Client struct {
+	gateway netip.Addr
+	timeout time.Duration
+
+	mu sync.Mutex
+	// localIP caches the resolved local IP address.
+	localIP netip.Addr
+	// lastEpoch is the last observed server epoch value.
+	lastEpoch uint32
+	// epochTime tracks when lastEpoch was received for state loss detection.
+	epochTime time.Time
+	// externalIP caches the external IP from the last successful MAP response.
+	externalIP netip.Addr
+	// epochStateLost is set when epoch indicates server restart.
+	epochStateLost bool
+}
+
+// NewClient creates a new PCP client for the gateway at the given IP.
+func NewClient(gateway net.IP) *Client {
+	addr, ok := netip.AddrFromSlice(gateway)
+	if !ok {
+		log.Debugf("invalid gateway IP: %v", gateway)
+	}
+	return &Client{
+		gateway: addr.Unmap(),
+		timeout: defaultTimeout,
+	}
+}
+
+// NewClientWithTimeout creates a new PCP client with a custom timeout.
+func NewClientWithTimeout(gateway net.IP, timeout time.Duration) *Client {
+	addr, ok := netip.AddrFromSlice(gateway)
+	if !ok {
+		log.Debugf("invalid gateway IP: %v", gateway)
+	}
+	return &Client{
+		gateway: addr.Unmap(),
+		timeout: timeout,
+	}
+}
+
+// SetLocalIP sets the local IP address to use in PCP requests.
+func (c *Client) SetLocalIP(ip net.IP) {
+	addr, ok := netip.AddrFromSlice(ip)
+	if !ok {
+		log.Debugf("invalid local IP: %v", ip)
+	}
+	c.mu.Lock()
+	c.localIP = addr.Unmap()
+	c.mu.Unlock()
+}
+
+// Gateway returns the gateway IP address.
+func (c *Client) Gateway() net.IP {
+	return c.gateway.AsSlice()
+}
+
+// Announce sends a PCP ANNOUNCE request to discover PCP support.
+// Returns the server's epoch time on success.
+func (c *Client) Announce(ctx context.Context) (epoch uint32, err error) {
+	localIP, err := c.getLocalIP()
+	if err != nil {
+		return 0, fmt.Errorf("get local IP: %w", err)
+	}
+
+	req := buildAnnounceRequest(localIP)
+	resp, err := c.sendRequest(ctx, req)
+	if err != nil {
+		return 0, fmt.Errorf("send announce: %w", err)
+	}
+
+	parsed, err := parseResponse(resp)
+	if err != nil {
+		return 0, fmt.Errorf("parse announce response: %w", err)
+	}
+
+	if parsed.ResultCode != ResultSuccess {
+		return 0, fmt.Errorf("PCP ANNOUNCE failed: %s", ResultCodeString(parsed.ResultCode))
+	}
+
+	c.mu.Lock()
+	if c.updateEpochLocked(parsed.Epoch) {
+		log.Warnf("PCP server epoch indicates state loss - mappings may need refresh")
+	}
+	c.mu.Unlock()
+	return parsed.Epoch, nil
+}
+
+// AddPortMapping requests a port mapping from the PCP server.
+func (c *Client) AddPortMapping(ctx context.Context, protocol string, internalPort int, lifetime time.Duration) (*MapResponse, error) {
+	return c.addPortMappingWithHint(ctx, protocol, internalPort, internalPort, netip.Addr{}, lifetime)
+}
+
+// AddPortMappingWithHint requests a port mapping with suggested external port and IP.
+// Use lifetime <= 0 to delete a mapping.
+func (c *Client) AddPortMappingWithHint(ctx context.Context, protocol string, internalPort, suggestedExtPort int, suggestedExtIP net.IP, lifetime time.Duration) (*MapResponse, error) {
+	var extIP netip.Addr
+	if suggestedExtIP != nil {
+		var ok bool
+		extIP, ok = netip.AddrFromSlice(suggestedExtIP)
+		if !ok {
+			log.Debugf("invalid suggested external IP: %v", suggestedExtIP)
+		}
+		extIP = extIP.Unmap()
+	}
+	return c.addPortMappingWithHint(ctx, protocol, internalPort, suggestedExtPort, extIP, lifetime)
+}
+
+func (c *Client) addPortMappingWithHint(ctx context.Context, protocol string, internalPort, suggestedExtPort int, suggestedExtIP netip.Addr, lifetime time.Duration) (*MapResponse, error) {
+	localIP, err := c.getLocalIP()
+	if err != nil {
+		return nil, fmt.Errorf("get local IP: %w", err)
+	}
+
+	proto, err := protocolNumber(protocol)
+	if err != nil {
+		return nil, fmt.Errorf("parse protocol: %w", err)
+	}
+
+	var nonce [12]byte
+	if _, err := rand.Read(nonce[:]); err != nil {
+		return nil, fmt.Errorf("generate nonce: %w", err)
+	}
+
+	// Convert lifetime to seconds. Lifetime 0 means delete, so only apply
+	// default for positive durations that round to 0 seconds.
+	var lifetimeSec uint32
+	if lifetime > 0 {
+		lifetimeSec = uint32(lifetime.Seconds())
+		if lifetimeSec == 0 {
+			lifetimeSec = DefaultLifetime
+		}
+	}
+
+	req := buildMapRequest(localIP, nonce, proto, uint16(internalPort), uint16(suggestedExtPort), suggestedExtIP, lifetimeSec)
+
+	resp, err := c.sendRequest(ctx, req)
+	if err != nil {
+		return nil, fmt.Errorf("send map request: %w", err)
+	}
+
+	mapResp, err := parseMapResponse(resp)
+	if err != nil {
+		return nil, fmt.Errorf("parse map response: %w", err)
+	}
+
+	if mapResp.Nonce != nonce {
+		return nil, fmt.Errorf("nonce mismatch in response")
+	}
+
+	if mapResp.Protocol != proto {
+		return nil, fmt.Errorf("protocol mismatch: requested %d, got %d", proto, mapResp.Protocol)
+	}
+	if mapResp.InternalPort != uint16(internalPort) {
+		return nil, fmt.Errorf("internal port mismatch: requested %d, got %d", internalPort, mapResp.InternalPort)
+	}
+
+	if mapResp.ResultCode != ResultSuccess {
+		return nil, &Error{
+			Code:    mapResp.ResultCode,
+			Message: ResultCodeString(mapResp.ResultCode),
+		}
+	}
+
+	c.mu.Lock()
+	if c.updateEpochLocked(mapResp.Epoch) {
+		log.Warnf("PCP server epoch indicates state loss - mappings may need refresh")
+	}
+	c.cacheExternalIPLocked(mapResp.ExternalIP)
+	c.mu.Unlock()
+	return mapResp, nil
+}
+
+// DeletePortMapping removes a port mapping by requesting zero lifetime.
+func (c *Client) DeletePortMapping(ctx context.Context, protocol string, internalPort int) error {
+	if _, err := c.addPortMappingWithHint(ctx, protocol, internalPort, 0, netip.Addr{}, 0); err != nil {
+		var pcpErr *Error
+		if errors.As(err, &pcpErr) && pcpErr.Code == ResultNotAuthorized {
+			return nil
+		}
+		return fmt.Errorf("delete mapping: %w", err)
+	}
+	return nil
+}
+
+// GetExternalAddress returns the external IP address.
+// First checks for a cached value from previous MAP responses.
+// If not cached, creates a short-lived mapping to discover the external IP.
+func (c *Client) GetExternalAddress(ctx context.Context) (net.IP, error) {
+	c.mu.Lock()
+	if c.externalIP.IsValid() {
+		ip := c.externalIP.AsSlice()
+		c.mu.Unlock()
+		return ip, nil
+	}
+	c.mu.Unlock()
+
+	// Use an ephemeral port in the dynamic range (49152-65535).
+	// Port 0 is not valid with UDP/TCP protocols per RFC 6887.
+	ephemeralPort := 49152 + int(uint16(time.Now().UnixNano()))%(65535-49152)
+
+	// Use minimal lifetime (1 second) for discovery.
+	resp, err := c.AddPortMapping(ctx, "udp", ephemeralPort, time.Second)
+	if err != nil {
+		return nil, fmt.Errorf("create temporary mapping: %w", err)
+	}
+
+	if err := c.DeletePortMapping(ctx, "udp", ephemeralPort); err != nil {
+		log.Debugf("cleanup temporary PCP mapping: %v", err)
+	}
+
+	return resp.ExternalIP.AsSlice(), nil
+}
+
+// LastEpoch returns the last observed server epoch value.
+// A decrease in epoch indicates the server may have restarted and mappings may be lost.
+func (c *Client) LastEpoch() uint32 {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	return c.lastEpoch
+}
+
+// EpochStateLost returns true if epoch state loss was detected and clears the flag.
+func (c *Client) EpochStateLost() bool {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	lost := c.epochStateLost
+	c.epochStateLost = false
+	return lost
+}
+
+// updateEpoch updates the epoch tracking and detects potential state loss.
+// Returns true if state loss was detected (server likely restarted).
+// Caller must hold c.mu.
+func (c *Client) updateEpochLocked(newEpoch uint32) bool {
+	now := time.Now()
+	stateLost := false
+
+	// RFC 6887 Section 8.5: Detect invalid epoch indicating server state loss.
+	// client_delta = time since last response
+	// server_delta = epoch change since last response
+	// Invalid if: client_delta+2 < server_delta - server_delta/16
+	//         OR: server_delta+2 < client_delta - client_delta/16
+	// The +2 handles quantization, /16 (6.25%) handles clock drift.
+	if !c.epochTime.IsZero() && c.lastEpoch > 0 {
+		clientDelta := uint32(now.Sub(c.epochTime).Seconds())
+		serverDelta := newEpoch - c.lastEpoch
+
+		// Check for epoch going backwards or jumping unexpectedly.
+		// Subtraction is safe: serverDelta/16 is always <= serverDelta.
+		if clientDelta+2 < serverDelta-(serverDelta/16) ||
+			serverDelta+2 < clientDelta-(clientDelta/16) {
+			stateLost = true
+			c.epochStateLost = true
+		}
+	}
+
+	c.lastEpoch = newEpoch
+	c.epochTime = now
+	return stateLost
+}
+
+// cacheExternalIP stores the external IP from a successful MAP response.
+// Caller must hold c.mu.
+func (c *Client) cacheExternalIPLocked(ip netip.Addr) {
+	if ip.IsValid() && !ip.IsUnspecified() {
+		c.externalIP = ip
+	}
+}
+
+// sendRequest sends a PCP request with retries per RFC 6887 Section 8.1.1.
+func (c *Client) sendRequest(ctx context.Context, req []byte) ([]byte, error) {
+	addr := &net.UDPAddr{IP: c.gateway.AsSlice(), Port: Port}
+
+	var lastErr error
+	delay := initialRetryDelay
+
+	for range maxRetries {
+		resp, err := c.sendOnce(ctx, addr, req)
+		if err == nil {
+			return resp, nil
+		}
+		lastErr = err
+
+		if ctx.Err() != nil {
+			return nil, ctx.Err()
+		}
+
+		// RFC 6887 Section 8.1.1: RT = (1 + RAND) * MIN(2 * RTprev, MRT)
+		// RAND is random between -0.1 and +0.1
+		select {
+		case <-ctx.Done():
+			return nil, ctx.Err()
+		case <-time.After(retryDelayWithJitter(delay)):
+		}
+		delay = min(delay*2, maxRetryDelay)
+	}
+
+	return nil, fmt.Errorf("PCP request failed after %d retries: %w", maxRetries, lastErr)
+}
+
+// retryDelayWithJitter applies RFC 6887 jitter: multiply by (1 + RAND) where RAND is [-0.1, +0.1].
+func retryDelayWithJitter(d time.Duration) time.Duration {
+	var b [1]byte
+	_, _ = rand.Read(b[:])
+	// Convert byte to range [-0.1, +0.1]: (b/255 * 0.2) - 0.1
+	jitter := (float64(b[0])/255.0)*0.2 - 0.1
+	return time.Duration(float64(d) * (1 + jitter))
+}
+
+func (c *Client) sendOnce(ctx context.Context, addr *net.UDPAddr, req []byte) ([]byte, error) {
+	// Use ListenUDP instead of DialUDP to validate response source address per RFC 6887 §8.3.
+	conn, err := net.ListenUDP("udp", nil)
+	if err != nil {
+		return nil, fmt.Errorf("listen: %w", err)
+	}
+	defer func() {
+		if err := conn.Close(); err != nil {
+			log.Debugf("close UDP connection: %v", err)
+		}
+	}()
+
+	timeout := c.timeout
+	if deadline, ok := ctx.Deadline(); ok {
+		if remaining := time.Until(deadline); remaining < timeout {
+			timeout = remaining
+		}
+	}
+
+	if err := conn.SetDeadline(time.Now().Add(timeout)); err != nil {
+		return nil, fmt.Errorf("set deadline: %w", err)
+	}
+
+	if _, err := conn.WriteToUDP(req, addr); err != nil {
+		return nil, fmt.Errorf("write: %w", err)
+	}
+
+	resp := make([]byte, responseBufferSize)
+	n, from, err := conn.ReadFromUDP(resp)
+	if err != nil {
+		return nil, fmt.Errorf("read: %w", err)
+	}
+
+	// RFC 6887 §8.3: Validate response came from expected PCP server.
+	if !from.IP.Equal(addr.IP) {
+		return nil, fmt.Errorf("response from unexpected source %s (expected %s)", from.IP, addr.IP)
+	}
+
+	return resp[:n], nil
+}
+
+func (c *Client) getLocalIP() (netip.Addr, error) {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+
+	if !c.localIP.IsValid() {
+		return netip.Addr{}, fmt.Errorf("local IP not set for gateway %s", c.gateway)
+	}
+	return c.localIP, nil
+}
+
+func protocolNumber(protocol string) (uint8, error) {
+	switch protocol {
+	case "udp", "UDP":
+		return ProtoUDP, nil
+	case "tcp", "TCP":
+		return ProtoTCP, nil
+	default:
+		return 0, fmt.Errorf("unsupported protocol: %s", protocol)
+	}
+}
+
+// Error represents a PCP error response.
+type Error struct {
+	Code    uint8
+	Message string
+}
+
+func (e *Error) Error() string {
+	return fmt.Sprintf("PCP error: %s (%d)", e.Message, e.Code)
+}

client/internal/portforward/pcp/client_test.go

@@ -0,0 +1,187 @@
+package pcp
+
+import (
+	"context"
+	"net"
+	"net/netip"
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestAddrConversion(t *testing.T) {
+	tests := []struct {
+		name string
+		addr netip.Addr
+	}{
+		{"IPv4", netip.MustParseAddr("192.168.1.100")},
+		{"IPv4 loopback", netip.MustParseAddr("127.0.0.1")},
+		{"IPv6", netip.MustParseAddr("2001:db8::1")},
+		{"IPv6 loopback", netip.MustParseAddr("::1")},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			b16 := addrTo16(tt.addr)
+
+			recovered := addrFrom16(b16)
+			assert.Equal(t, tt.addr, recovered, "address should round-trip")
+		})
+	}
+}
+
+func TestBuildAnnounceRequest(t *testing.T) {
+	clientIP := netip.MustParseAddr("192.168.1.100")
+	req := buildAnnounceRequest(clientIP)
+
+	require.Len(t, req, headerSize)
+	assert.Equal(t, byte(Version), req[0], "version")
+	assert.Equal(t, byte(OpAnnounce), req[1], "opcode")
+
+	// Check client IP is properly encoded as IPv4-mapped IPv6
+	assert.Equal(t, byte(0xff), req[18], "IPv4-mapped prefix byte 10")
+	assert.Equal(t, byte(0xff), req[19], "IPv4-mapped prefix byte 11")
+	assert.Equal(t, byte(192), req[20], "IP octet 1")
+	assert.Equal(t, byte(168), req[21], "IP octet 2")
+	assert.Equal(t, byte(1), req[22], "IP octet 3")
+	assert.Equal(t, byte(100), req[23], "IP octet 4")
+}
+
+func TestBuildMapRequest(t *testing.T) {
+	clientIP := netip.MustParseAddr("192.168.1.100")
+	nonce := [12]byte{1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12}
+	req := buildMapRequest(clientIP, nonce, ProtoUDP, 51820, 51820, netip.Addr{}, 3600)
+
+	require.Len(t, req, mapRequestSize)
+	assert.Equal(t, byte(Version), req[0], "version")
+	assert.Equal(t, byte(OpMap), req[1], "opcode")
+
+	// Lifetime at bytes 4-7
+	assert.Equal(t, uint32(3600), (uint32(req[4])<<24)|(uint32(req[5])<<16)|(uint32(req[6])<<8)|uint32(req[7]), "lifetime")
+
+	// Nonce at bytes 24-35
+	assert.Equal(t, nonce[:], req[24:36], "nonce")
+
+	// Protocol at byte 36
+	assert.Equal(t, byte(ProtoUDP), req[36], "protocol")
+
+	// Internal port at bytes 40-41
+	assert.Equal(t, uint16(51820), (uint16(req[40])<<8)|uint16(req[41]), "internal port")
+
+	// External port at bytes 42-43
+	assert.Equal(t, uint16(51820), (uint16(req[42])<<8)|uint16(req[43]), "external port")
+}
+
+func TestParseResponse(t *testing.T) {
+	// Construct a valid ANNOUNCE response
+	resp := make([]byte, headerSize)
+	resp[0] = Version
+	resp[1] = OpAnnounce | OpReply
+	// Result code = 0 (success)
+	// Lifetime = 0
+	// Epoch = 12345
+	resp[8] = 0
+	resp[9] = 0
+	resp[10] = 0x30
+	resp[11] = 0x39
+
+	parsed, err := parseResponse(resp)
+	require.NoError(t, err)
+	assert.Equal(t, uint8(Version), parsed.Version)
+	assert.Equal(t, uint8(OpAnnounce|OpReply), parsed.Opcode)
+	assert.Equal(t, uint8(ResultSuccess), parsed.ResultCode)
+	assert.Equal(t, uint32(12345), parsed.Epoch)
+}
+
+func TestParseResponseErrors(t *testing.T) {
+	t.Run("too short", func(t *testing.T) {
+		_, err := parseResponse([]byte{1, 2, 3})
+		assert.Error(t, err)
+	})
+
+	t.Run("wrong version", func(t *testing.T) {
+		resp := make([]byte, headerSize)
+		resp[0] = 1 // Wrong version
+		resp[1] = OpReply
+		_, err := parseResponse(resp)
+		assert.Error(t, err)
+	})
+
+	t.Run("missing reply bit", func(t *testing.T) {
+		resp := make([]byte, headerSize)
+		resp[0] = Version
+		resp[1] = OpAnnounce // Missing OpReply bit
+		_, err := parseResponse(resp)
+		assert.Error(t, err)
+	})
+}
+
+func TestResultCodeString(t *testing.T) {
+	assert.Equal(t, "SUCCESS", ResultCodeString(ResultSuccess))
+	assert.Equal(t, "NOT_AUTHORIZED", ResultCodeString(ResultNotAuthorized))
+	assert.Equal(t, "ADDRESS_MISMATCH", ResultCodeString(ResultAddressMismatch))
+	assert.Contains(t, ResultCodeString(255), "UNKNOWN")
+}
+
+func TestProtocolNumber(t *testing.T) {
+	proto, err := protocolNumber("udp")
+	require.NoError(t, err)
+	assert.Equal(t, uint8(ProtoUDP), proto)
+
+	proto, err = protocolNumber("tcp")
+	require.NoError(t, err)
+	assert.Equal(t, uint8(ProtoTCP), proto)
+
+	proto, err = protocolNumber("UDP")
+	require.NoError(t, err)
+	assert.Equal(t, uint8(ProtoUDP), proto)
+
+	_, err = protocolNumber("icmp")
+	assert.Error(t, err)
+}
+
+func TestClientCreation(t *testing.T) {
+	gateway := netip.MustParseAddr("192.168.1.1").AsSlice()
+
+	client := NewClient(gateway)
+	assert.Equal(t, net.IP(gateway), client.Gateway())
+	assert.Equal(t, defaultTimeout, client.timeout)
+
+	clientWithTimeout := NewClientWithTimeout(gateway, 5*time.Second)
+	assert.Equal(t, 5*time.Second, clientWithTimeout.timeout)
+}
+
+func TestNATType(t *testing.T) {
+	n := NewNAT(netip.MustParseAddr("192.168.1.1").AsSlice(), netip.MustParseAddr("192.168.1.100").AsSlice())
+	assert.Equal(t, "PCP", n.Type())
+}
+
+// Integration test - skipped unless PCP_TEST_GATEWAY env is set
+func TestClientIntegration(t *testing.T) {
+	t.Skip("Integration test - run manually with PCP_TEST_GATEWAY=<gateway-ip>")
+
+	gateway := netip.MustParseAddr("10.0.1.1").AsSlice()   // Change to your test gateway
+	localIP := netip.MustParseAddr("10.0.1.100").AsSlice() // Change to your local IP
+
+	client := NewClient(gateway)
+	client.SetLocalIP(localIP)
+	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
+	defer cancel()
+
+	// Test ANNOUNCE
+	epoch, err := client.Announce(ctx)
+	require.NoError(t, err)
+	t.Logf("Server epoch: %d", epoch)
+
+	// Test MAP
+	resp, err := client.AddPortMapping(ctx, "udp", 51820, 1*time.Hour)
+	require.NoError(t, err)
+	t.Logf("Mapping: internal=%d external=%d externalIP=%s",
+		resp.InternalPort, resp.ExternalPort, resp.ExternalIP)
+
+	// Cleanup
+	err = client.DeletePortMapping(ctx, "udp", 51820)
+	require.NoError(t, err)
+}

client/internal/portforward/pcp/nat.go

@@ -0,0 +1,209 @@
+package pcp
+
+import (
+	"context"
+	"fmt"
+	"net"
+	"net/netip"
+	"sync"
+	"time"
+
+	log "github.com/sirupsen/logrus"
+
+	"github.com/libp2p/go-nat"
+	"github.com/libp2p/go-netroute"
+)
+
+var _ nat.NAT = (*NAT)(nil)
+
+// NAT implements the go-nat NAT interface using PCP.
+// Supports dual-stack (IPv4 and IPv6) when available.
+// All methods are safe for concurrent use.
+//
+// TODO: IPv6 pinholes use the local IPv6 address. If the address changes
+// (e.g., due to SLAAC rotation or network change), the pinhole becomes stale
+// and needs to be recreated with the new address.
+type NAT struct {
+	client *Client
+
+	mu sync.RWMutex
+	// client6 is the IPv6 PCP client, nil if IPv6 is unavailable.
+	client6 *Client
+	// localIP6 caches the local IPv6 address used for PCP requests.
+	localIP6 netip.Addr
+}
+
+// NewNAT creates a new NAT instance backed by PCP.
+func NewNAT(gateway, localIP net.IP) *NAT {
+	client := NewClient(gateway)
+	client.SetLocalIP(localIP)
+	return &NAT{
+		client: client,
+	}
+}
+
+// Type returns "PCP" as the NAT type.
+func (n *NAT) Type() string {
+	return "PCP"
+}
+
+// GetDeviceAddress returns the gateway IP address.
+func (n *NAT) GetDeviceAddress() (net.IP, error) {
+	return n.client.Gateway(), nil
+}
+
+// GetExternalAddress returns the external IP address.
+func (n *NAT) GetExternalAddress() (net.IP, error) {
+	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
+	defer cancel()
+	return n.client.GetExternalAddress(ctx)
+}
+
+// GetInternalAddress returns the local IP address used to communicate with the gateway.
+func (n *NAT) GetInternalAddress() (net.IP, error) {
+	addr, err := n.client.getLocalIP()
+	if err != nil {
+		return nil, err
+	}
+	return addr.AsSlice(), nil
+}
+
+// AddPortMapping creates a port mapping on both IPv4 and IPv6 (if available).
+func (n *NAT) AddPortMapping(ctx context.Context, protocol string, internalPort int, _ string, timeout time.Duration) (int, error) {
+	resp, err := n.client.AddPortMapping(ctx, protocol, internalPort, timeout)
+	if err != nil {
+		return 0, fmt.Errorf("add mapping: %w", err)
+	}
+
+	n.mu.RLock()
+	client6 := n.client6
+	localIP6 := n.localIP6
+	n.mu.RUnlock()
+
+	if client6 == nil {
+		return int(resp.ExternalPort), nil
+	}
+
+	if _, err := client6.AddPortMapping(ctx, protocol, internalPort, timeout); err != nil {
+		log.Warnf("IPv6 PCP mapping failed (continuing with IPv4): %v", err)
+		return int(resp.ExternalPort), nil
+	}
+
+	log.Infof("created IPv6 PCP pinhole: %s:%d", localIP6, internalPort)
+	return int(resp.ExternalPort), nil
+}
+
+// DeletePortMapping removes a port mapping from both IPv4 and IPv6.
+func (n *NAT) DeletePortMapping(ctx context.Context, protocol string, internalPort int) error {
+	err := n.client.DeletePortMapping(ctx, protocol, internalPort)
+
+	n.mu.RLock()
+	client6 := n.client6
+	n.mu.RUnlock()
+
+	if client6 != nil {
+		if err6 := client6.DeletePortMapping(ctx, protocol, internalPort); err6 != nil {
+			log.Warnf("IPv6 PCP delete mapping failed: %v", err6)
+		}
+	}
+
+	if err != nil {
+		return fmt.Errorf("delete mapping: %w", err)
+	}
+	return nil
+}
+
+// CheckServerHealth sends an ANNOUNCE to verify the server is still responsive.
+// Returns the current epoch and whether the server may have restarted (epoch state loss detected).
+func (n *NAT) CheckServerHealth(ctx context.Context) (epoch uint32, serverRestarted bool, err error) {
+	epoch, err = n.client.Announce(ctx)
+	if err != nil {
+		return 0, false, fmt.Errorf("announce: %w", err)
+	}
+	return epoch, n.client.EpochStateLost(), nil
+}
+
+// DiscoverPCP attempts to discover a PCP-capable gateway.
+// Returns a NAT interface if PCP is supported, or an error otherwise.
+// Discovers both IPv4 and IPv6 gateways when available.
+func DiscoverPCP(ctx context.Context) (nat.NAT, error) {
+	gateway, localIP, err := getDefaultGateway()
+	if err != nil {
+		return nil, fmt.Errorf("get default gateway: %w", err)
+	}
+
+	client := NewClient(gateway)
+	client.SetLocalIP(localIP)
+	if _, err := client.Announce(ctx); err != nil {
+		return nil, fmt.Errorf("PCP announce: %w", err)
+	}
+
+	result := &NAT{client: client}
+	discoverIPv6(ctx, result)
+
+	return result, nil
+}
+
+func discoverIPv6(ctx context.Context, result *NAT) {
+	gateway6, localIP6, err := getDefaultGateway6()
+	if err != nil {
+		log.Debugf("IPv6 gateway discovery failed: %v", err)
+		return
+	}
+
+	client6 := NewClient(gateway6)
+	client6.SetLocalIP(localIP6)
+	if _, err := client6.Announce(ctx); err != nil {
+		log.Debugf("PCP IPv6 announce failed: %v", err)
+		return
+	}
+
+	addr, ok := netip.AddrFromSlice(localIP6)
+	if !ok {
+		log.Debugf("invalid IPv6 local IP: %v", localIP6)
+		return
+	}
+	result.mu.Lock()
+	result.client6 = client6
+	result.localIP6 = addr
+	result.mu.Unlock()
+	log.Debugf("PCP IPv6 gateway discovered: %s (local: %s)", gateway6, localIP6)
+}
+
+// getDefaultGateway returns the default IPv4 gateway and local IP using the system routing table.
+func getDefaultGateway() (gateway net.IP, localIP net.IP, err error) {
+	router, err := netroute.New()
+	if err != nil {
+		return nil, nil, err
+	}
+
+	_, gateway, localIP, err = router.Route(net.IPv4zero)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	if gateway == nil {
+		return nil, nil, nat.ErrNoNATFound
+	}
+
+	return gateway, localIP, nil
+}
+
+// getDefaultGateway6 returns the default IPv6 gateway IP address using the system routing table.
+func getDefaultGateway6() (gateway net.IP, localIP net.IP, err error) {
+	router, err := netroute.New()
+	if err != nil {
+		return nil, nil, err
+	}
+
+	_, gateway, localIP, err = router.Route(net.IPv6zero)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	if gateway == nil {
+		return nil, nil, nat.ErrNoNATFound
+	}
+
+	return gateway, localIP, nil
+}

client/internal/portforward/pcp/protocol.go

@@ -0,0 +1,225 @@
+// Package pcp implements the Port Control Protocol (RFC 6887).
+//
+// # Implemented Features
+//
+//   - ANNOUNCE opcode: Discovers PCP server support
+//   - MAP opcode: Creates/deletes port mappings (IPv4 NAT) and firewall pinholes (IPv6)
+//   - Dual-stack: Simultaneous IPv4 and IPv6 support via separate clients
+//   - Nonce validation: Prevents response spoofing
+//   - Epoch tracking: Detects server restarts per Section 8.5
+//   - RFC-compliant retry timing: 3s initial, exponential backoff to 1024s max (Section 8.1.1)
+//
+// # Not Implemented
+//
+//   - PEER opcode: For outbound peer connections (not needed for inbound NAT traversal)
+//   - THIRD_PARTY option: For managing mappings on behalf of other devices
+//   - PREFER_FAILURE option: Requires exact external port or fail (IPv4 NAT only, not needed for IPv6 pinholing)
+//   - FILTER option: To restrict remote peer addresses
+//
+// These optional features are omitted because the primary use case is simple
+// port forwarding for WireGuard, which only requires MAP with default behavior.
+package pcp
+
+import (
+	"encoding/binary"
+	"fmt"
+	"net/netip"
+)
+
+const (
+	// Version is the PCP protocol version (RFC 6887).
+	Version = 2
+
+	// Port is the standard PCP server port.
+	Port = 5351
+
+	// DefaultLifetime is the default requested mapping lifetime in seconds.
+	DefaultLifetime = 7200 // 2 hours
+
+	// Header sizes
+	headerSize     = 24
+	mapPayloadSize = 36
+	mapRequestSize = headerSize + mapPayloadSize // 60 bytes
+)
+
+// Opcodes
+const (
+	OpAnnounce = 0
+	OpMap      = 1
+	OpPeer     = 2
+	OpReply    = 0x80 // OR'd with opcode in responses
+)
+
+// Protocol numbers for MAP requests
+const (
+	ProtoUDP = 17
+	ProtoTCP = 6
+)
+
+// Result codes (RFC 6887 Section 7.4)
+const (
+	ResultSuccess              = 0
+	ResultUnsuppVersion        = 1
+	ResultNotAuthorized        = 2
+	ResultMalformedRequest     = 3
+	ResultUnsuppOpcode         = 4
+	ResultUnsuppOption         = 5
+	ResultMalformedOption      = 6
+	ResultNetworkFailure       = 7
+	ResultNoResources          = 8
+	ResultUnsuppProtocol       = 9
+	ResultUserExQuota          = 10
+	ResultCannotProvideExt     = 11
+	ResultAddressMismatch      = 12
+	ResultExcessiveRemotePeers = 13
+)
+
+// ResultCodeString returns a human-readable string for a result code.
+func ResultCodeString(code uint8) string {
+	switch code {
+	case ResultSuccess:
+		return "SUCCESS"
+	case ResultUnsuppVersion:
+		return "UNSUPP_VERSION"
+	case ResultNotAuthorized:
+		return "NOT_AUTHORIZED"
+	case ResultMalformedRequest:
+		return "MALFORMED_REQUEST"
+	case ResultUnsuppOpcode:
+		return "UNSUPP_OPCODE"
+	case ResultUnsuppOption:
+		return "UNSUPP_OPTION"
+	case ResultMalformedOption:
+		return "MALFORMED_OPTION"
+	case ResultNetworkFailure:
+		return "NETWORK_FAILURE"
+	case ResultNoResources:
+		return "NO_RESOURCES"
+	case ResultUnsuppProtocol:
+		return "UNSUPP_PROTOCOL"
+	case ResultUserExQuota:
+		return "USER_EX_QUOTA"
+	case ResultCannotProvideExt:
+		return "CANNOT_PROVIDE_EXTERNAL"
+	case ResultAddressMismatch:
+		return "ADDRESS_MISMATCH"
+	case ResultExcessiveRemotePeers:
+		return "EXCESSIVE_REMOTE_PEERS"
+	default:
+		return fmt.Sprintf("UNKNOWN(%d)", code)
+	}
+}
+
+// Response represents a parsed PCP response header.
+type Response struct {
+	Version    uint8
+	Opcode     uint8
+	ResultCode uint8
+	Lifetime   uint32
+	Epoch      uint32
+}
+
+// MapResponse contains the full response to a MAP request.
+type MapResponse struct {
+	Response
+	Nonce        [12]byte
+	Protocol     uint8
+	InternalPort uint16
+	ExternalPort uint16
+	ExternalIP   netip.Addr
+}
+
+// addrTo16 converts an address to its 16-byte IPv4-mapped IPv6 representation.
+func addrTo16(addr netip.Addr) [16]byte {
+	if addr.Is4() {
+		return netip.AddrFrom4(addr.As4()).As16()
+	}
+	return addr.As16()
+}
+
+// addrFrom16 extracts an address from a 16-byte representation, unmapping IPv4.
+func addrFrom16(b [16]byte) netip.Addr {
+	return netip.AddrFrom16(b).Unmap()
+}
+
+// buildAnnounceRequest creates a PCP ANNOUNCE request packet.
+func buildAnnounceRequest(clientIP netip.Addr) []byte {
+	req := make([]byte, headerSize)
+	req[0] = Version
+	req[1] = OpAnnounce
+	mapped := addrTo16(clientIP)
+	copy(req[8:24], mapped[:])
+	return req
+}
+
+// buildMapRequest creates a PCP MAP request packet.
+func buildMapRequest(clientIP netip.Addr, nonce [12]byte, protocol uint8, internalPort, suggestedExtPort uint16, suggestedExtIP netip.Addr, lifetime uint32) []byte {
+	req := make([]byte, mapRequestSize)
+
+	// Header
+	req[0] = Version
+	req[1] = OpMap
+	binary.BigEndian.PutUint32(req[4:8], lifetime)
+	mapped := addrTo16(clientIP)
+	copy(req[8:24], mapped[:])
+
+	// MAP payload
+	copy(req[24:36], nonce[:])
+	req[36] = protocol
+	binary.BigEndian.PutUint16(req[40:42], internalPort)
+	binary.BigEndian.PutUint16(req[42:44], suggestedExtPort)
+	if suggestedExtIP.IsValid() {
+		extMapped := addrTo16(suggestedExtIP)
+		copy(req[44:60], extMapped[:])
+	}
+
+	return req
+}
+
+// parseResponse parses the common PCP response header.
+func parseResponse(data []byte) (*Response, error) {
+	if len(data) < headerSize {
+		return nil, fmt.Errorf("response too short: %d bytes", len(data))
+	}
+
+	resp := &Response{
+		Version:    data[0],
+		Opcode:     data[1],
+		ResultCode: data[3], // Byte 2 is reserved, byte 3 is result code (RFC 6887 §7.2)
+		Lifetime:   binary.BigEndian.Uint32(data[4:8]),
+		Epoch:      binary.BigEndian.Uint32(data[8:12]),
+	}
+
+	if resp.Version != Version {
+		return nil, fmt.Errorf("unsupported PCP version: %d", resp.Version)
+	}
+
+	if resp.Opcode&OpReply == 0 {
+		return nil, fmt.Errorf("response missing reply bit: opcode=0x%02x", resp.Opcode)
+	}
+
+	return resp, nil
+}
+
+// parseMapResponse parses a complete MAP response.
+func parseMapResponse(data []byte) (*MapResponse, error) {
+	if len(data) < mapRequestSize {
+		return nil, fmt.Errorf("MAP response too short: %d bytes", len(data))
+	}
+
+	resp, err := parseResponse(data)
+	if err != nil {
+		return nil, fmt.Errorf("parse header: %w", err)
+	}
+
+	mapResp := &MapResponse{
+		Response:     *resp,
+		Protocol:     data[36],
+		InternalPort: binary.BigEndian.Uint16(data[40:42]),
+		ExternalPort: binary.BigEndian.Uint16(data[42:44]),
+		ExternalIP:   addrFrom16([16]byte(data[44:60])),
+	}
+	copy(mapResp.Nonce[:], data[24:36])
+
+	return mapResp, nil
+}

client/internal/portforward/state.go

@@ -0,0 +1,63 @@
+//go:build !js
+
+package portforward
+
+import (
+	"context"
+	"fmt"
+
+	"github.com/libp2p/go-nat"
+	log "github.com/sirupsen/logrus"
+
+	"github.com/netbirdio/netbird/client/internal/portforward/pcp"
+)
+
+// discoverGateway is the function used for NAT gateway discovery.
+// It can be replaced in tests to avoid real network operations.
+// Tries PCP first, then falls back to NAT-PMP/UPnP.
+var discoverGateway = defaultDiscoverGateway
+
+func defaultDiscoverGateway(ctx context.Context) (nat.NAT, error) {
+	pcpGateway, err := pcp.DiscoverPCP(ctx)
+	if err == nil {
+		return pcpGateway, nil
+	}
+	log.Debugf("PCP discovery failed: %v, trying NAT-PMP/UPnP", err)
+
+	return nat.DiscoverGateway(ctx)
+}
+
+// State is persisted only for crash recovery cleanup
+type State struct {
+	InternalPort uint16 `json:"internal_port,omitempty"`
+	Protocol     string `json:"protocol,omitempty"`
+}
+
+func (s *State) Name() string {
+	return "port_forward_state"
+}
+
+// Cleanup implements statemanager.CleanableState for crash recovery
+func (s *State) Cleanup() error {
+	if s.InternalPort == 0 {
+		return nil
+	}
+
+	log.Infof("cleaning up stale port mapping for port %d", s.InternalPort)
+
+	ctx, cancel := context.WithTimeout(context.Background(), discoveryTimeout)
+	defer cancel()
+
+	gateway, err := discoverGateway(ctx)
+	if err != nil {
+		// Discovery failure is not an error - gateway may not exist
+		log.Debugf("cleanup: no gateway found: %v", err)
+		return nil
+	}
+
+	if err := gateway.DeletePortMapping(ctx, s.Protocol, int(s.InternalPort)); err != nil {
+		return fmt.Errorf("delete port mapping: %w", err)
+	}
+
+	return nil
+}

client/internal/routemanager/manager.go

@@ -168,6 +168,7 @@ func (m *DefaultManager) setupAndroidRoutes(config ManagerConfig) {
 			NetworkType: route.IPv4Network,
 		}
 		cr = append(cr, fakeIPRoute)
+		m.notifier.SetFakeIPRoute(fakeIPRoute)
 	}
 
 	m.notifier.SetInitialClientRoutes(cr, routesForComparison)

client/internal/routemanager/notifier/notifier_android.go

@@ -16,6 +16,7 @@ import (
 type Notifier struct {
 	initialRoutes []*route.Route
 	currentRoutes []*route.Route
+	fakeIPRoute   *route.Route
 
 	listener    listener.NetworkChangeListener
 	listenerMux sync.Mutex
@@ -31,13 +32,17 @@ func (n *Notifier) SetListener(listener listener.NetworkChangeListener) {
 	n.listener = listener
 }
 
-// SetInitialClientRoutes stores the full initial route set (including fake IP blocks)
-// and a separate comparison set (without fake IP blocks) for diff detection.
+// SetInitialClientRoutes stores the initial route sets for TUN configuration.
 func (n *Notifier) SetInitialClientRoutes(initialRoutes []*route.Route, routesForComparison []*route.Route) {
 	n.initialRoutes = filterStatic(initialRoutes)
 	n.currentRoutes = filterStatic(routesForComparison)
 }
 
+// SetFakeIPRoute stores the fake IP route to be included in every TUN rebuild.
+func (n *Notifier) SetFakeIPRoute(r *route.Route) {
+	n.fakeIPRoute = r
+}
+
 func (n *Notifier) OnNewRoutes(idMap route.HAMap) {
 	var newRoutes []*route.Route
 	for _, routes := range idMap {
@@ -69,7 +74,9 @@ func (n *Notifier) notify() {
 	}
 
 	allRoutes := slices.Clone(n.currentRoutes)
-	allRoutes = append(allRoutes, n.extraInitialRoutes()...)
+	if n.fakeIPRoute != nil {
+		allRoutes = append(allRoutes, n.fakeIPRoute)
+	}
 
 	routeStrings := n.routesToStrings(allRoutes)
 	sort.Strings(routeStrings)
@@ -78,23 +85,6 @@ func (n *Notifier) notify() {
 	}(n.listener)
 }
 
-// extraInitialRoutes returns initialRoutes whose network prefix is absent
-// from currentRoutes (e.g. the fake IP block added at setup time).
-func (n *Notifier) extraInitialRoutes() []*route.Route {
-	currentNets := make(map[netip.Prefix]struct{}, len(n.currentRoutes))
-	for _, r := range n.currentRoutes {
-		currentNets[r.Network] = struct{}{}
-	}
-
-	var extra []*route.Route
-	for _, r := range n.initialRoutes {
-		if _, ok := currentNets[r.Network]; !ok {
-			extra = append(extra, r)
-		}
-	}
-	return extra
-}
-
 func filterStatic(routes []*route.Route) []*route.Route {
 	out := make([]*route.Route, 0, len(routes))
 	for _, r := range routes {

client/internal/routemanager/notifier/notifier_ios.go

@@ -34,6 +34,10 @@ func (n *Notifier) SetInitialClientRoutes([]*route.Route, []*route.Route) {
 	// iOS doesn't care about initial routes
 }
 
+func (n *Notifier) SetFakeIPRoute(*route.Route) {
+	// Not used on iOS
+}
+
 func (n *Notifier) OnNewRoutes(route.HAMap) {
 	// Not used on iOS
 }
@@ -53,7 +57,6 @@ func (n *Notifier) OnNewPrefixes(prefixes []netip.Prefix) {
 	n.currentPrefixes = newNets
 	n.notify()
 }
-
 func (n *Notifier) notify() {
 	n.listenerMux.Lock()
 	defer n.listenerMux.Unlock()

client/internal/routemanager/notifier/notifier_other.go

@@ -23,6 +23,10 @@ func (n *Notifier) SetInitialClientRoutes([]*route.Route, []*route.Route) {
 	// Not used on non-mobile platforms
 }
 
+func (n *Notifier) SetFakeIPRoute(*route.Route) {
+	// Not used on non-mobile platforms
+}
+
 func (n *Notifier) OnNewRoutes(idMap route.HAMap) {
 	// Not used on non-mobile platforms
 }